lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  PHC 
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:	Thu, 09 Jun 2011 17:03:55 -0700
From:	Tim Chen <>
To:	Eric Dumazet <>
Cc:	David Miller <>,
	netdev <>, Andi Kleen <>
Subject: Re: [PATCH net-next-2.6] inetpeer: lower false sharing effect

On Thu, 2011-06-09 at 08:26 +0200, Eric Dumazet wrote:
> Profiles show false sharing in addr_compare() because refcnt/dtime
> changes dirty the first inet_peer cache line, where are lying the keys
> used at lookup time. If many cpus are calling inet_getpeer() and
> inet_putpeer(), or need frag ids, addr_compare() is in 2nd position in
> "perf top".

I've applied both inetpeer patches.  I also no longer have inet_getpeer
and inet_putpeer and addr_compare in my profile.  Instead, neighbor
lookup is now dominant.  See profile below.

When I retest with original 3.0-rc2 kernel, inet_putpeer no longer shows
up, wonder if dst->peer was not set for some reason. 


-     27.06%     memcached  [kernel.kallsyms]             [k] atomic_add_unless.clone.34
   - atomic_add_unless.clone.34
      - 99.97% neigh_lookup
-     13.33%     memcached  [kernel.kallsyms]             [k] atomic_dec_and_test
   - atomic_dec_and_test
      - 99.89% dst_destroy
         - dst_release
            - 98.12% skb_dst_drop.clone.55
               + sch_direct_xmit
            + 1.88% skb_release_head_state
-      3.26%     memcached  [kernel.kallsyms]             [k] do_raw_spin_lock
   - do_raw_spin_lock
      - 92.24% _raw_spin_lock
         + 41.39% sch_direct_xmit

To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to
More majordomo info at

Powered by blists - more mailing lists