Re: [Bug #11308] tbench regression on each kernel release from2.6.22 -> 2.6.28

[David Miller]

From: Ingo Molnar <mingo@xxxxxxx>
Date: Mon, 17 Nov 2008 19:49:51 +0100

> 
> * Ingo Molnar <mingo@xxxxxxx> wrote:
> 
> 4> The place for the sock_rfree() hit looks a bit weird, and i'll 
> > investigate it now a bit more to place the real overhead point 
> > properly. (i already mapped the test-bit overhead: that comes from 
> > napi_disable_pending())
> 
> ok, here's a new set of profiles. (again for tbench 64-thread on a 
> 16-way box, with v2.6.28-rc5-19-ge14c8bf and with the kernel config i 
> posted before.)

Again, do a non-NMI profile and the top (at least for me)
looks like this:

samples  %        app name                 symbol name
473       6.3928  vmlinux                  finish_task_switch
349       4.7169  vmlinux                  tcp_v4_rcv
327       4.4195  vmlinux                  U3copy_from_user
322       4.3519  vmlinux                  tl0_linux32
178       2.4057  vmlinux                  tcp_ack
170       2.2976  vmlinux                  tcp_sendmsg
167       2.2571  vmlinux                  U3copy_to_user

That tcp_v4_rcv() hit is %98 on the wake_up() call it does.
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