Skip to content

L
linux
Switch branch/tag
  1. 13 Nov, 2011 12 commits
  3. 12 Nov, 2011 4 commits
  5. 09 Nov, 2011 2 commits
    • Eric Dumazet's avatar
      ipv4: PKTINFO doesnt need dst reference · d826eb14
      Eric Dumazet authored 
      Le lundi 07 novembre 2011 à 15:33 +0100, Eric Dumazet a écrit :

> At least, in recent kernels we dont change dst->refcnt in forwarding
> patch (usinf NOREF skb->dst)
>
> One particular point is the atomic_inc(dst->refcnt) we have to perform
> when queuing an UDP packet if socket asked PKTINFO stuff (for example a
> typical DNS server has to setup this option)
>
> I have one patch somewhere that stores the information in skb->cb[] and
> avoid the atomic_{inc|dec}(dst->refcnt).
>

OK I found it, I did some extra tests and believe its ready.

[PATCH net-next] ipv4: IP_PKTINFO doesnt need dst reference

When a socket uses IP_PKTINFO notifications, we currently force a dst
reference for each received skb. Reader has to access dst to get needed
information (rt_iif & rt_spec_dst) and must release dst reference.

We also forced a dst reference if skb was put in socket backlog, even
without IP_PKTINFO handling. This happens under stress/load.

We can instead store the needed information in skb->cb[], so that only
softirq handler really access dst, improving cache hit ratios.

This removes two atomic operations per packet, and false sharing as
well.

On a benchmark using a mono threaded receiver (doing only recvmsg()
calls), I can reach 720.000 pps instead of 570.000 pps.

IP_PKTINFO is typically used by DNS servers, and any multihomed aware
UDP application.
Signed-off-by: default avatarEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      d826eb14
    • Eric Dumazet's avatar
      ipv4: reduce percpu needs for icmpmsg mibs · acb32ba3
      Eric Dumazet authored 
      Reading /proc/net/snmp on a machine with a lot of cpus is very expensive
(can be ~88000 us).

This is because ICMPMSG MIB uses 4096 bytes per cpu, and folding values
for all possible cpus can read 16 Mbytes of memory.

ICMP messages are not considered as fast path on a typical server, and
eventually few cpus handle them anyway. We can afford an atomic
operation instead of using percpu data.

This saves 4096 bytes per cpu and per network namespace.
Signed-off-by: default avatarEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      acb32ba3
  7. 08 Nov, 2011 19 commits
  9. 07 Nov, 2011 3 commits
    • Al Viro's avatar
      VFS: we need to set LOOKUP_JUMPED on mountpoint crossing · a3fbbde7
      Al Viro authored 
      Mountpoint crossing is similar to following procfs symlinks - we do
not get ->d_revalidate() called for dentry we have arrived at, with
unpleasant consequences for NFS4.

Simple way to reproduce the problem in mainline:

    cat >/tmp/a.c <<'EOF'
    #include <unistd.h>
    #include <fcntl.h>
    #include <stdio.h>
    main()
    {
            struct flock fl = {.l_type = F_RDLCK, .l_whence = SEEK_SET, .l_len = 1};
            if (fcntl(0, F_SETLK, &fl))
                    perror("setlk");
    }
    EOF
    cc /tmp/a.c -o /tmp/test

then on nfs4:

    mount --bind file1 file2
    /tmp/test < file1		# ok
    /tmp/test < file2		# spews "setlk: No locks available"...

What happens is the missing call of ->d_revalidate() after mountpoint
crossing and that's where NFS4 would issue OPEN request to server.

The fix is simple - treat mountpoint crossing the same way we deal with
following procfs-style symlinks.  I.e.  set LOOKUP_JUMPED...

Cc: stable@kernel.org
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      a3fbbde7
    • Linus Torvalds's avatar
      Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip · 54a0f913
      Linus Torvalds authored 
      * 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf top: Fix live annotation in the --stdio interface
  perf top tui: Don't recalc column widths considering just the first page
  perf report: Add progress bar when processing time ordered events
  perf hists browser: Warn about lost events
  perf tools: Fix a typo of command name as trace-cmd
  perf hists: Fix recalculation of total_period when sorting entries
  perf header: Fix build on old systems
  perf ui browser: Handle K_RESIZE in dialog windows
  perf ui browser: No need to switch char sets that often
  perf hists browser: Use K_TIMER
  perf ui: Rename ui__warning_paranoid to ui__error_paranoid
  perf ui: Reimplement the popup windows using libslang
  perf ui: Reimplement ui__popup_menu using ui__browser
  perf ui: Reimplement ui_helpline using libslang
  perf ui: Improve handling sigwinch a bit
  perf ui progress: Reimplement using slang
  perf evlist: Fix grouping of multiple events
      54a0f913
    • Tony Lindgren's avatar
      Merge branch 'fixes-modulesplit' into fixes · d30cc16c
      Tony Lindgren authored
      d30cc16c
GitLab Nexedi Edition | About GitLab | About Nexedi | 沪ICP备2021021310号-2 | 沪ICP备2021021310号-7