From: Andi Kleen <andi@firstfloor.org>
To: "Patrick J. LoPresti" <lopresti@gmail.com>
Cc: linux-fsdevel@vger.kernel.org, linux-nfs@vger.kernel.org,
linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: Proposal: Use hi-res clock for file timestamps
Date: Tue, 17 Aug 2010 16:54:03 +0200 [thread overview]
Message-ID: <87aaolwar8.fsf@basil.nowhere.org> (raw)
In-Reply-To: <AANLkTimnyXKahtjaFeSsgcq=xMy-pP3na1jidQhZ-dt2@mail.gmail.com> (Patrick J. LoPresti's message of "Fri, 13 Aug 2010 11:25:49 -0700")
"Patrick J. LoPresti" <lopresti@gmail.com> writes:
>
> 1) Anybody who cares about file system performance is already using
> "noatime" or "relatime", which mitigates the hit greatly.
Consider mtime.
> If the above patch is too slow for some architectures, how about
> making it a configuration option? Call it "CONFIG_1980S_FILE_TICK",
> have it default to YES on the architectures that care and NO on
> anything remotely modern and sane.
>
> OK that's my proposal. Bash away.
I suspect it will be a performance disaster on x86 for VFS intensive
applications on capable file systems. VFS is very performance
critical. These checks lurk on unexpected places too, e.g. on /dev
access.
Even TSC is much slower than just reading the variable.
Also you should check if the file system granuality
even supports it, it's completely wasted on a ext3 for example.
Maybe as a optional sysctl, default to off.
-Andi
--
ak@linux.intel.com -- Speaking for myself only.
next prev parent reply other threads:[~2010-08-17 14:54 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-08-13 18:25 Proposal: Use hi-res clock for file timestamps Patrick J. LoPresti
2010-08-13 18:45 ` john stultz
2010-08-13 18:57 ` Patrick J. LoPresti
2010-08-13 19:09 ` john stultz
2010-08-13 20:53 ` Patrick J. LoPresti
2010-08-14 16:45 ` Patrick J. LoPresti
2010-08-15 1:50 ` Bret Towe
2010-08-13 19:57 ` Jim Rees
2010-08-13 20:26 ` john stultz
2010-08-13 20:52 ` Jim Rees
2010-08-17 14:54 ` Andi Kleen [this message]
2010-08-17 17:41 ` J. Bruce Fields
2010-08-17 18:29 ` Andi Kleen
2010-08-17 18:50 ` Patrick J. LoPresti
2010-08-17 19:04 ` J. Bruce Fields
2010-08-17 19:18 ` Patrick J. LoPresti
2010-08-17 19:39 ` Alan Cox
2010-08-17 19:29 ` J. Bruce Fields
2010-08-17 19:52 ` Alan Cox
2010-08-18 5:53 ` Neil Brown
2010-08-18 14:46 ` Patrick J. LoPresti
2010-08-18 17:32 ` J. Bruce Fields
2010-08-18 18:15 ` Chuck Lever
2010-08-18 23:41 ` Neil Brown
2010-08-19 0:52 ` Neil Brown
2010-08-19 2:08 ` J. Bruce Fields
2010-08-19 2:44 ` Neil Brown
2010-08-19 22:46 ` J. Bruce Fields
2010-08-18 23:47 ` Neil Brown
2010-08-18 17:50 ` Andi Kleen
2010-08-18 18:54 ` J. Bruce Fields
2010-08-18 19:25 ` Andi Kleen
2010-08-18 19:30 ` J. Bruce Fields
2010-08-17 19:34 ` Patrick J. LoPresti
2010-08-17 19:54 ` Alan Cox
2010-08-17 19:43 ` Patrick J. LoPresti
2010-08-17 19:45 ` J. Bruce Fields
2010-08-18 18:12 ` J. Bruce Fields
2010-08-19 1:41 ` john stultz
2010-08-19 2:31 ` J. Bruce Fields
2010-08-19 3:17 ` john stultz
2010-08-19 22:53 ` J. Bruce Fields
2010-08-18 18:20 ` David Woodhouse
2010-08-18 18:32 ` Patrick J. LoPresti
2010-08-18 18:53 ` Andi Kleen
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