- 06 May, 2009 2 commits
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Steven Rostedt authored
This patch adds code that can benchmark the ring buffer as well as test it. This code can be compiled into the kernel (not recommended) or as a module. A separate ring buffer is used to not interfer with other users, like ftrace. It creates a producer and a consumer (option to disable creation of the consumer) and will run for 10 seconds, then sleep for 10 seconds and then repeat. While running, the producer will write 10 byte loads into the ring buffer with just putting in the current CPU number. The reader will continually try to read the buffer. The reader will alternate from reading the buffer via event by event, or by full pages. The output is a pr_info, thus it will fill up the syslogs. Starting ring buffer hammer End ring buffer hammer Time: 9000349 (usecs) Overruns: 12578640 Read: 5358440 (by events) Entries: 0 Total: 17937080 Missed: 0 Hit: 17937080 Entries per millisec: 1993 501 ns per entry Sleeping for 10 secs Starting ring buffer hammer End ring buffer hammer Time: 9936350 (usecs) Overruns: 0 Read: 28146644 (by pages) Entries: 74 Total: 28146718 Missed: 0 Hit: 28146718 Entries per millisec: 2832 353 ns per entry Sleeping for 10 secs Time: is the time the test ran Overruns: the number of events that were overwritten and not read Read: the number of events read (either by pages or events) Entries: the number of entries left in the buffer (the by pages will only read full pages) Total: Entries + Read + Overruns Missed: the number of entries that failed to write Hit: the number of entries that were written The above example shows that it takes ~353 nanosecs per entry when there is a reader, reading by pages (and no overruns) The event by event reader slowed the producer down to 501 nanosecs. [ Impact: see how changes to the ring buffer affect stability and performance ] Signed-off-by:Steven Rostedt <rostedt@goodmis.org>
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Steven Rostedt authored
In the hot path of the ring buffer "__rb_reserve_next" there's a big if statement that does not even return back to the work flow. code; if (cross to next page) { [ lots of code ] return; } more code; The condition is even the unlikely path, although we do not denote it with an unlikely because gcc is fine with it. The condition is true when the write crosses a page boundary, and we need to start at a new page. Having this if statement makes it hard to read, but calling another function to do the work is also not appropriate, because we are using a lot of variables that were set before the if statement, and we do not want to send them as parameters. This patch changes it to a goto: code; if (cross to next page) goto next_page; more code; return; next_page: [ lots of code] This makes the code easier to understand, and a bit more obvious. The output from gcc is practically identical. For some reason, gcc decided to use different registers when I switched it to a goto. But other than that, the logic is the same. [ Impact: easier to read code ] Signed-off-by:
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- 05 May, 2009 9 commits
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Steven Rostedt authored
When adding the EXPORT_SYMBOL to some of the tracing API, I accidently used EXPORT_SYMBOL instead of EXPORT_SYMBOL_GPL. This patch fixes that mistake. [ Impact: export the tracing code only for GPL modules ] Reported-by:
Christoph Hellwig <hch@lst.de> Signed-off-by:
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Tim Abbott authored
The only references in the kernel to the .text.sched section are in recordmcount.pl. Since the code it has is intended to be example code it should refer to real kernel sections. So change it to .sched.text instead. [ Impact: consistency in comments ] Signed-off-by:
Tim Abbott <tabbott@mit.edu> LKML-Reference: <1241136371-10768-1-git-send-email-tabbott@mit.edu> Acked-by:
Sam Ravnborg <sam@ravnborg.org> Signed-off-by:
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Steven Rostedt authored
As a precaution, it is best to disable writing to the ring buffers when reseting them. [ Impact: prevent weird things if write happens during reset ] Signed-off-by: -
Steven Rostedt authored
In the swap page ring buffer code that is used by the ftrace splice code, we scan the page to increment the counter of entries read. With the number of entries already in the page we simply need to add it. [ Impact: speed up reading page from ring buffer ] Signed-off-by: -
Steven Rostedt authored
Currently, when the ring buffer writer overflows the buffer and must write over non consumed data, we increment the overrun counter by reading the entries on the page we are about to overwrite. This reads the entries one by one. This is not very effecient. This patch adds another entry counter into each buffer page descriptor that keeps track of the number of entries on the page. Now on overwrite, the overrun counter simply needs to add the number of entries that is on the page it is about to overwrite. [ Impact: speed up of ring buffer in overwrite mode ] Signed-off-by: -
Steven Rostedt authored
The entries counter in cpu buffer is not atomic. It can be updated by other interrupts or from another CPU (readers). But making entries into "atomic_t" causes an atomic operation that can hurt performance. Instead we convert it to a local_t that will increment a counter with a local CPU atomic operation (if the arch supports it). Instead of fighting with readers and overwrites that decrement the counter, I added a "read" counter. Every time a reader reads an entry it is incremented. We already have a overrun counter and with that, the entries counter and the read counter, we can calculate the total number of entries in the buffer with: (entries - overrun) - read As long as the total number of entries in the ring buffer is less than the word size, this will work. But since the entries counter was previously a long, this is no different than what we had before. Thanks to Andrew Morton for pointing out in the first version that atomic_t does not replace unsigned long. I switched to atomic_long_t even though it is signed. A negative count is most likely a bug. [ Impact: keep accurate count of cpu buffer entries ] Signed-off-by: -
Steven Rostedt authored
This patch adds stats to the ftrace ring buffers: # cat /debugfs/tracing/per_cpu/cpu0/stats entries: 42360 overrun: 30509326 commit overrun: 0 nmi dropped: 0 Where entries are the total number of data entries in the buffer. overrun is the number of entries not consumed and were overwritten by the writer. commit overrun is the number of entries dropped due to nested writers wrapping the buffer before the initial writer finished the commit. nmi dropped is the number of entries dropped due to the ring buffer lock being held when an nmi was going to write to the ring buffer. Note, this field will be meaningless and will go away when the ring buffer becomes lockless. [ Impact: let userspace know what is happening in the ring buffers ] Signed-off-by: -
Steven Rostedt authored
The WARN_ON in the ring buffer when a commit is preempted and the buffer is filled by preceding writes can happen in normal operations. The WARN_ON makes it look like a bug, not to mention, because it does not stop tracing and calls printk which can also recurse, this is prone to deadlock (the WARN_ON is not in a position to recurse). This patch removes the WARN_ON and replaces it with a counter that can be retrieved by a tracer. This counter is called commit_overrun. While at it, I added a nmi_dropped counter to count any time an NMI entry is dropped because the NMI could not take the spinlock. [ Impact: prevent deadlock by printing normal case warning ] Signed-off-by: -
Steven Rostedt authored
I'm adding a module to do a series of tests on the ring buffer as well as benchmarks. This module needs to have more of the ring buffer API exported. There's nothing wrong with reading the ring buffer from a module. [ Impact: allow modules to read pages from the ring buffer ] Signed-off-by:
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- 01 May, 2009 3 commits
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Jason Baron authored
Document irqs for the newly created docbook. [ Impact: add documentation ] Signed-off-by:
Jason Baron <jbaron@redhat.com> Acked-by:
Randy Dunlap <randy.dunlap@oracle.com> Cc: akpm@linux-foundation.org Cc: rostedt@goodmis.org Cc: fweisbec@gmail.com Cc: mathieu.desnoyers@polymtl.ca Cc: wcohen@redhat.com LKML-Reference: <73ff42be3420157667ec548e9b0e409c3cfad05f.1241107197.git.jbaron@redhat.com> Signed-off-by:
Ingo Molnar <mingo@elte.hu>
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Jason Baron authored
Add tracepoint docbook. This will help us document and understand what tracepoints are in the kernel. Since there are multiple macros, and files that contain tracepoints. [ Impact: add documentation ] Signed-off-by:
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Jason Baron authored
Add support to kernel-doc for tracepoint comments above TRACE_EVENT() macro definitions. Paves the way for tracepoint docbook. [ Impact: extend DocBook infrastructure ] Signed-off-by:
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- 29 Apr, 2009 11 commits
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Heiko Carstens authored
"tracing: create automated trace defines" causes this compile error on s390, as reported by Sachin Sant against linux-next: kernel/built-in.o: In function `__do_softirq': (.text+0x1c680): undefined reference to `__tracepoint_softirq_entry' This happens because the definitions of the softirq tracepoints were moved from kernel/softirq.c to kernel/irq/handle.c. Since s390 doesn't support generic hardirqs handle.c doesn't get compiled and the definitions are missing. So move the tracepoints to softirq.c again. [ Impact: fix build failure on s390 ] Reported-by:
Sachin Sant <sachinp@in.ibm.com> Signed-off-by:
Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: fweisbec@gmail.com LKML-Reference: <20090429135139.5fac79b8@osiris.boeblingen.de.ibm.com> Signed-off-by:
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Tom Zanussi authored
Replace the current event parser hack with a better one. Filters are no longer specified predicate by predicate, but all at once and can use parens and any of the following operators: numeric fields: ==, !=, <, <=, >, >= string fields: ==, != predicates can be combined with the logical operators: &&, || examples: "common_preempt_count > 4" > filter "((sig >= 10 && sig < 15) || sig == 17) && comm != bash" > filter If there was an error, the erroneous string along with an error message can be seen by looking at the filter e.g.: ((sig >= 10 && sig < 15) || dsig == 17) && comm != bash ^ parse_error: Field not found Currently the caret for an error always appears at the beginning of the filter; a real position should be used, but the error message should be useful even without it. To clear a filter, '0' can be written to the filter file. Filters can also be set or cleared for a complete subsystem by writing the same filter as would be written to an individual event to the filter file at the root of the subsytem. Note however, that if any event in the subsystem lacks a field specified in the filter being set, the set will fail and all filters in the subsytem are automatically cleared. This change from the previous version was made because using only the fields that happen to exist for a given event would most likely result in a meaningless filter. Because the logical operators are now implemented as predicates, the maximum number of predicates in a filter was increased from 8 to 16. [ Impact: add new, extended trace-filter implementation ] Signed-off-by:
Tom Zanussi <tzanussi@gmail.com> Acked-by:
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Tom Zanussi authored
The new filter comparison ops need to be able to distinguish between signed and unsigned field types, so add an is_signed flag/param to the event field struct/trace_define_fields(). Also define a simple macro, is_signed_type() to determine the signedness at compile time, used in the trace macros. If the is_signed_type() macro won't work with a specific type, a new slightly modified version of TRACE_FIELD() called TRACE_FIELD_SIGN(), allows the signedness to be set explicitly. [ Impact: extend trace-filter code for new feature ] Signed-off-by:
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Tom Zanussi authored
Create a new event_filter object, and move the pred-related members out of the call and subsystem objects and into the filter object - the details of the filter implementation don't need to be exposed in the call and subsystem in any case, and it will also help make the new parser implementation a little cleaner. [ Impact: refactor trace-filter code to prepare for new features ] Signed-off-by:
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Stuart Bennett authored
Follow up to afcfe024 in Linus' tree ("x86: mmiotrace: quieten spurious warning message") Signed-off-by:
Stuart Bennett <stuart@freedesktop.org> Acked-by:
Pekka Paalanen <pq@iki.fi> Cc: Steven Rostedt <rostedt@goodmis.org> LKML-Reference: <1240946271-7083-5-git-send-email-stuart@freedesktop.org> Signed-off-by:
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Stuart Bennett authored
* change function names to clear_* from set_*: in reality we only clear and restore page presence, and never unconditionally set present. Using clear_*({true, false}, ...) is therefore more honest than set_*({false, true}, ...) * upgrade presence storage to pteval_t: doing user-space tracing will require saving and manipulation of the _PAGE_PROTNONE bit, in addition to the existing _PAGE_PRESENT changes, and having multiple bools stored and passed around does not seem optimal [ Impact: refactor, clean up mmiotrace code ] Signed-off-by: -
Stuart Bennett authored
kmmio_probe being *p and kmmio_fault_page being sometimes *f and sometimes *p is not helpful. [ Impact: cleanup ] Signed-off-by:
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Steven Rostedt authored
The warning output in trace_recursive_lock uses %d for a long when it should be %ld. [ Impact: fix compile warning ] Signed-off-by: -
Steven Rostedt authored
Splice works with pages, it is much more effecient to use an entire page than to copy bits over several pages. Using logdev to trace the internals of the splice mechanism, I was able to see that splice can be very aggressive. When tracing is occurring, and the reader caught up to the writer, and the writer is on the reader page, the reader will copy what is there into the splice page. Splice may iterate over several pages and if the writer is still writing to the page, the reader will keep copying bits to new pages to pass to userspace. This patch changes it to only pass data to userspace if the page is full (the writer has left the page). This has a small side effect that splice can not read a partial page, and must wait for the page to fill. This should not be an issue. If tracing has stopped, then a use of "read" will still read all of the page. [ Impact: better performance for ring buffer splice code ] Signed-off-by: -
Steven Rostedt authored
The splice code allocates a page even when the ring buffer is empty. It detects the ring buffer being empty when it it fails to copy anything from the ring buffer into the page. This patch adds a check to see if there is anything in the ring buffer before allocating a page. Thanks to logdev for letting me trace the tracer to find this. [ Impact: speed up due to removing unnecessary allocation ] Signed-off-by: -
Steven Rostedt authored
The pages allocated for the splice binary buffer did not initialize the ref count correctly. This caused pages not to be freed and causes a drastic memory leak. Thanks to logdev I was able to trace the tracer to find where the leak was. [ Impact: stop memory leak when using splice ] Signed-off-by:
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- 28 Apr, 2009 1 commit
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Steven Rostedt authored
ftrace_dump is used for printing out the contents of the ftrace ring buffer to the console on failure. Currently it uses a spinlock to synchronize the output from multiple failures on different CPUs. This spin lock currently is a normal spinlock and can cause issues with lockdep and lock tracing. This patch converts it to raw since it is for error handling only. The lock is local to the ftrace_dump and is not used by any other infrastructure. [ Impact: prevent ftrace_dump from locking up by internal tracing ] Signed-off-by:
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- 26 Apr, 2009 1 commit
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Steven Rostedt authored
For proper module reference counting, the file_operations that modules use must have the "owner" field set to the module. Unfortunately, the trace events use share file_operations. The same file_operations are used by all both kernel core and all modules. This patch makes the modules allocate their own file_operations and copies the functions from the core kernel. This allows those file operations to be owned by the module. Care is taken to free this code on module unload. Thanks to Greg KH for reminding me that file_operations must be owned by the module to have reference counting take place. [ Impact: fix modular tracepoints / potential crash ] Signed-off-by:
Greg Kroah-Hartman <gregkh@suse.de>
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- 25 Apr, 2009 1 commit
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Steven Rostedt authored
With modules being able to add trace events, and the max trace event counter is 16 bits (65536) we can overflow the counter easily with a simple while loop adding and removing modules that contain trace events. This patch links together the registered trace events and on overflow searches for available trace event ids. It will still fail if over 65536 events are registered, but considering that a typical kernel only has 22000 functions, 65000 events should be sufficient. Reported-by:
Li Zefan <lizf@cn.fujitsu.com> Signed-off-by:
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- 24 Apr, 2009 9 commits
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Steven Rostedt authored
The TRACE_FORMAT macro has been deprecated by the TRACE_EVENT macro. There are no more users. All new users must use the TRACE_EVENT macro. [ Impact: remove old functionality ] Cc: Peter Zijlstra <peterz@infradead.org> Signed-off-by: -
Steven Rostedt authored
The TRACE_FORMAT will soon be deprecated. This patch converts it to the TRACE_EVENT macro. Note, this change should also speed up the tracing. [ Impact: remove a user of deprecated TRACE_FORMAT ] Cc: Jason Baron <jbaron@redhat.com> Signed-off-by: -
Steven Rostedt authored
The TRACE_FORMAT will soon be deprecated. This patch converts it to the TRACE_EVENT macro. Note, this change should also speed up the tracing. [ Impact: remove a user of deprecated TRACE_FORMAT ] Cc: Peter Zijlstra <peterz@infradead.org> Signed-off-by: -
Lai Jiangshan authored
RB_MAX_SMALL_DATA = 28bytes is too small for most tracers, it wastes an 'u32' to save the actually length for events which data size > 28. This fix uses compressed event header and enlarges RB_MAX_SMALL_DATA. [ Impact: saves about 0%-12.5%(depends on tracer) memory in ring_buffer ] Signed-off-by:
Lai Jiangshan <laijs@cn.fujitsu.com> LKML-Reference: <49F13189.3090000@cn.fujitsu.com> Signed-off-by:
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Steven Rostedt authored
In case a module uses the TRACE_EVENT macro for creating automated events in ftrace, it may choose to use a different file name than the defined system name, or choose to use a different path than the default "include/trace/events" include path. If this is done, then before including trace/define_trace.h the header would define either "TRACE_INCLUDE_FILE" for the file name or "TRACE_INCLUDE_PATH" for the include path. If it does not define these, then the define_trace.h defines them instead. If define trace defines them, then define_trace.h should also undefine them before exiting. To do this a macro is used to note this: #ifndef TRACE_INCLUDE_FILE # define TRACE_INCLUDE_FILE TRACE_SYSTEM # define UNDEF_TRACE_INCLUDE_FILE #endif [...] #ifdef UNDEF_TRACE_INCLUDE_FILE # undef TRACE_INCLUDE_FILE # undef UNDEF_TRACE_INCLUDE_FILE #endif The UNDEF_TRACE_INCLUDE_FILE acts as a CPP variable to know to undef the TRACE_INCLUDE_FILE before leaving define_trace.h. Unfortunately, due to cut and paste errors, the macros between FILE and PATH got mixed up. [ Impact: undef TRACE_INCLUDE_FILE and/or TRACE_INCLUDE_PATH when needed ] Signed-off-by: -
Chris Wright authored
currently these are paravirtulaized, doesn't appear any callers rely on this (no pv_ops backends are using native_tlb and overriding cr3/4 access). [ Impact: fix lockdep warning with paravirt and function tracer ] Signed-off-by:
Chris Wright <chrisw@sous-sol.org> LKML-Reference: <20090423172138.GR3036@sequoia.sous-sol.org> Signed-off-by:
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Steven Rostedt authored
The events exported by TRACE_EVENT are automated and are guaranteed to be correct when used. The internal ftrace structures on the other hand are more manually exported. These require the ftrace maintainer to make sure they are up to date. This patch adds a size check to help flag when a type changes in an internal ftrace data structure, and the update needs to be reflected in the export. If a export is incorrect, then the only harm is that the user space tools will not know how to correctly read the internal structures of ftrace. [ Impact: help prevent inconsistent ftrace format print outs ] Signed-off-by:Steven Rostedt <srostedt@redhat.com>
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Steven Rostedt authored
With the new event tracing registration, we must increase the number of events that can be registered. Currently the type field is only one byte, which leaves us only 256 possible events. Since we do not save the CPU number in the tracer anymore (it is determined by the per cpu ring buffer that is used) we have an extra byte to use. This patch increases the size of type from 1 byte (256 events) to 2 bytes (65,536 events). It also adds a WARN_ON_ONCE if we exceed that limit. [ Impact: allow more than 255 events ] Signed-off-by: -
Steven Rostedt authored
The code had the following outside the lock: if (next != wakeup_task) return; pc = preempt_count(); /* The task we are waiting for is waking up */ data = wakeup_trace->data[wakeup_cpu]; On initialization, wakeup_task is NULL and wakeup_cpu -1. This code is not under a lock. If wakeup_task is set on another CPU as that task is waking up, we can see the wakeup_task before wakeup_cpu is set. If we read wakeup_cpu while it is still -1 then we will have a bad data pointer. This patch moves the reading of wakeup_cpu within the protection of the spinlock used to protect the writing of wakeup_cpu and wakeup_task. [ Impact: remove possible race causing invalid pointer dereference ] Reported-by:Maneesh Soni <maneesh@in.ibm.com> Signed-off-by:
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- 22 Apr, 2009 3 commits
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Frederic Weisbecker authored
The __get_str() macro is used in a code part then its content should be protected with parenthesis. [ Impact: make macro definition more robust ] Reported-by:
Frederic Weisbecker <fweisbec@gmail.com>
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Frederic Weisbecker authored
Now that we can support the dynamic sized string, make the lock tracing able to use it, making it safe against modules removal and consuming the right amount of memory needed for each lock name Changes in v2: adapt to the __ending_string() updates and the opening_string() removal. [ Impact: protect lock tracer against module removal ] Signed-off-by: -
Frederic Weisbecker authored
This patch provides the support for dynamic size strings on event tracing. The key concept is to use a structure with an ending char array field of undefined size and use such ability to allocate the minimal size on the ring buffer to make one or more string entries fit inside, as opposite to a fixed length strings with upper bound. The strings themselves are represented using fields which have an offset value from the beginning of the entry. This patch provides three new macros: __string(item, src) This one declares a string to the structure inside TP_STRUCT__entry. You need to provide the name of the string field and the source that will be copied inside. This will also add the dynamic size of the string needed for the ring buffer entry allocation. A stack allocated structure is used to temporarily store the offset of each strings, avoiding double calls to strlen() on each event insertion. __get_str(field) This one will give you a pointer to the string you have created. This is an abstract helper to resolve the absolute address given the field name which is a relative address from the beginning of the trace_structure. __assign_str(dst, src) Use this macro to automatically perform the string copy from src to dst. src must be a variable to assign and dst is the name of a __string field. Example on how to use it: TRACE_EVENT(my_event, TP_PROTO(char *src1, char *src2), TP_ARGS(src1, src2), TP_STRUCT__entry( __string(str1, src1) __string(str2, src2) ), TP_fast_assign( __assign_str(str1, src1); __assign_str(str2, src2); ), TP_printk("%s %s", __get_str(src1), __get_str(src2)) ) Of course you can mix-up any __field or __array inside this TRACE_EVENT. The position of the __string or __assign_str doesn't matter. Changes in v2: Address the suggestion of Steven Rostedt: drop the opening_string() macro and redefine __ending_string() to get the size of the string to be copied instead of overwritting the whole ring buffer allocation. Changes in v3: Address other suggestions of Steven Rostedt and Peter Zijlstra with some changes: drop the __ending_string and the need to have only one string field. Use offsets instead of absolute addresses. [ Impact: allow more compact memory usage for string tracing ] Signed-off-by:
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