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From: John Baldwin <jhb@freebsd.org>
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Cc: Andre Oppermann <andre@freebsd.org>, Luigi Rizzo <rizzo@iet.unipi.it>,
	current@freebsd.org, net@freebsd.org
Subject: Re: Some performance measurements on the FreeBSD network stack
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On Thursday, April 19, 2012 4:46:22 pm Luigi Rizzo wrote:
> What might be moderately expensive are the critical_enter()/critical_exit()
> calls around individual allocations.
> The allocation happens while the code has already an exclusive
> lock on so->snd_buf so a pool of fresh buffers could be attached
> there.

Keep in mind that in the common case critical_enter() and critical_exit()
should be very cheap as they should just do td->td_critnest++ and
td->td_critnest--.  critical_enter() should probably be inlined if KTR
is not enabled.

-- 
John Baldwin