Documentation: x86: convert tlb.txt to reST

This converts the plain text documentation to reStructuredText format and
add it to Sphinx TOC tree. No essential content change.
Signed-off-by: Changbin Du <changbin.du@gmail.com>
Reviewed-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/x86/index.rst

@@ -15,3 +15,4 @@ x86-specific Documentation
    entry_64
    earlyprintk
    zero-page
+   tlb

Documentation/x86/tlb.txt → Documentation/x86/tlb.rst

+.. SPDX-License-Identifier: GPL-2.0
+
+=======
+The TLB
+=======
+
 When the kernel unmaps or modified the attributes of a range of
 memory, it has two choices:
+
  1. Flush the entire TLB with a two-instruction sequence.  This is
     a quick operation, but it causes collateral damage: TLB entries
     from areas other than the one we are trying to flush will be
@@ -10,6 +17,7 @@ memory, it has two choices:
     damage to other TLB entries.
 
 Which method to do depends on a few things:
+
  1. The size of the flush being performed.  A flush of the entire
     address space is obviously better performed by flushing the
     entire TLB than doing 2^48/PAGE_SIZE individual flushes.
@@ -33,7 +41,7 @@ well.  There is essentially no "right" point to choose.
 You may be doing too many individual invalidations if you see the
 invlpg instruction (or instructions _near_ it) show up high in
 profiles.  If you believe that individual invalidations being
-called too often, you can lower the tunable:
+called too often, you can lower the tunable::
 
 	/sys/kernel/debug/x86/tlb_single_page_flush_ceiling
 
@@ -43,7 +51,7 @@ Setting it to 1 is a very conservative setting and it should
 never need to be 0 under normal circumstances.
 
 Despite the fact that a single individual flush on x86 is
-guaranteed to flush a full 2MB [1], hugetlbfs always uses the full
+guaranteed to flush a full 2MB [1]_, hugetlbfs always uses the full
 flushes.  THP is treated exactly the same as normal memory.
 
 You might see invlpg inside of flush_tlb_mm_range() show up in
@@ -54,15 +62,15 @@ Essentially, you are balancing the cycles you spend doing invlpg
 with the cycles that you spend refilling the TLB later.
 
 You can measure how expensive TLB refills are by using
-performance counters and 'perf stat', like this:
+performance counters and 'perf stat', like this::
 
-perf stat -e
-	cpu/event=0x8,umask=0x84,name=dtlb_load_misses_walk_duration/,
-	cpu/event=0x8,umask=0x82,name=dtlb_load_misses_walk_completed/,
-	cpu/event=0x49,umask=0x4,name=dtlb_store_misses_walk_duration/,
-	cpu/event=0x49,umask=0x2,name=dtlb_store_misses_walk_completed/,
-	cpu/event=0x85,umask=0x4,name=itlb_misses_walk_duration/,
-	cpu/event=0x85,umask=0x2,name=itlb_misses_walk_completed/
+  perf stat -e
+    cpu/event=0x8,umask=0x84,name=dtlb_load_misses_walk_duration/,
+    cpu/event=0x8,umask=0x82,name=dtlb_load_misses_walk_completed/,
+    cpu/event=0x49,umask=0x4,name=dtlb_store_misses_walk_duration/,
+    cpu/event=0x49,umask=0x2,name=dtlb_store_misses_walk_completed/,
+    cpu/event=0x85,umask=0x4,name=itlb_misses_walk_duration/,
+    cpu/event=0x85,umask=0x2,name=itlb_misses_walk_completed/
 
 That works on an IvyBridge-era CPU (i5-3320M).  Different CPUs
 may have differently-named counters, but they should at least
@@ -70,6 +78,6 @@ be there in some form.  You can use pmu-tools 'ocperf list'
 (https://github.com/andikleen/pmu-tools) to find the right
 counters for a given CPU.
 
-1. A footnote in Intel's SDM "4.10.4.2 Recommended Invalidation"
+.. [1] A footnote in Intel's SDM "4.10.4.2 Recommended Invalidation"
    says: "One execution of INVLPG is sufficient even for a page
    with size greater than 4 KBytes."