From: P@draigBrady.com
To: Andrea Arcangeli <andrea@novell.com>
Cc: netdev@oss.sgi.com, Ingo Molnar <mingo@elte.hu>
Subject: Re: gettimeofday scalability
Date: Tue, 05 Oct 2004 20:16:33 +0100 [thread overview]
Message-ID: <4162F311.4050009@draigBrady.com> (raw)
In-Reply-To: <20041005185553.GG26820@dualathlon.random>
Andrea Arcangeli wrote:
> On Tue, Oct 05, 2004 at 05:36:06PM +0100, P@draigBrady.com wrote:
>
>>So can anyone summarise the relative merits of these locking
>>mechanisms, before I start benchmarking?
>
>
> frlock/seqlock (2.4/2.6 respectively) is the way to go, no write
> starvation, and zero cacheline bouncing.
Cheers.
Perhaps the confusing comment wrt brlock at the
top of seqlock.h can be changed so?
> upgrade to x86-64, there I implemented gettimeofday with vsyscalls which
> also avoids entering exiting userspace which becomes the by far biggest
> overhead after using seqlock. (speedup is tenfold or so)
This is all in kernel space.
However Stephen's suggestion of reading the tsc in user space
may be a runner, as I just care about relative times.
thanks guys!
Pádraig.
next prev parent reply other threads:[~2004-10-05 19:16 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-10-05 16:36 gettimeofday scalability P
2004-10-05 18:35 ` David S. Miller
2004-10-05 18:48 ` Stephen Hemminger
2004-10-05 18:55 ` Andrea Arcangeli
2004-10-05 19:16 ` P [this message]
2004-10-05 19:35 ` Andrea Arcangeli
2004-10-05 19:18 ` Ingo Molnar
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