netdev - Re: [PATCH] tcp: syncookies: do not use getnstimeofday()

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Message-ID: <20140319225642.GA5080@breakpoint.cc>
Date:	Wed, 19 Mar 2014 23:56:42 +0100
From:	Florian Westphal <fw@...len.de>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	Florian Westphal <fw@...len.de>, netdev@...r.kernel.org
Subject: Re: [PATCH] tcp: syncookies: do not use getnstimeofday()

Eric Dumazet <eric.dumazet@...il.com> wrote:
> While it is true that getnstimeofday() uses about 40 cycles if TSC
> is available, it can use 1600 cycles if hpet is the clocksource.

Ouch.  Why is secure_tcp_sequence_number also using
ktime_get_real/getnstimeofday?

clock drift when other cpu is used?

[ Just curious; I have no objections to this patch ]
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