From: Andi Kleen <andi@firstfloor.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Wu Fengguang <fengguang.wu@intel.com>,
Linux Memory Management List <linux-mm@kvack.org>,
linux-fsdevel@vger.kernel.org, Ingo Molnar <mingo@elte.hu>,
Jens Axboe <jens.axboe@oracle.com>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Rik van Riel <riel@redhat.com>,
LKML <linux-kernel@vger.kernel.org>,
Andi Kleen <andi@firstfloor.org>
Subject: Re: [PATCH 5/8] readahead: add /debug/readahead/stats
Date: Tue, 22 Nov 2011 00:32:55 +0100 [thread overview]
Message-ID: <20111121233255.GF24062@one.firstfloor.org> (raw)
In-Reply-To: <20111121152958.e4fd76d4.akpm@linux-foundation.org>
> I may be wrong, but I don't think the CPU cost of this code matters a
> lot. People will rarely turn it on and disk IO is a lot slower than
> CPU actions and it's waaaaaaay more important to get high-quality info
> about readahead than it is to squeeze out a few CPU cycles.
In its current form it would cache line bounce, which tends to be
extremly slow. But the solution is probably to make it per CPU.
-Andi
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
WARNING: multiple messages have this Message-ID (diff)
From: Andi Kleen <andi@firstfloor.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Wu Fengguang <fengguang.wu@intel.com>,
Linux Memory Management List <linux-mm@kvack.org>,
linux-fsdevel@vger.kernel.org, Ingo Molnar <mingo@elte.hu>,
Jens Axboe <jens.axboe@oracle.com>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Rik van Riel <riel@redhat.com>,
LKML <linux-kernel@vger.kernel.org>,
Andi Kleen <andi@firstfloor.org>
Subject: Re: [PATCH 5/8] readahead: add /debug/readahead/stats
Date: Tue, 22 Nov 2011 00:32:55 +0100 [thread overview]
Message-ID: <20111121233255.GF24062@one.firstfloor.org> (raw)
In-Reply-To: <20111121152958.e4fd76d4.akpm@linux-foundation.org>
> I may be wrong, but I don't think the CPU cost of this code matters a
> lot. People will rarely turn it on and disk IO is a lot slower than
> CPU actions and it's waaaaaaay more important to get high-quality info
> about readahead than it is to squeeze out a few CPU cycles.
In its current form it would cache line bounce, which tends to be
extremly slow. But the solution is probably to make it per CPU.
-Andi
next prev parent reply other threads:[~2011-11-21 23:32 UTC|newest]
Thread overview: 116+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-11-21 9:18 [PATCH 0/8] readahead stats/tracing, backwards prefetching and more Wu Fengguang
2011-11-21 9:18 ` Wu Fengguang
2011-11-21 9:18 ` Wu Fengguang
2011-11-21 9:18 ` [PATCH 1/8] block: limit default readahead size for small devices Wu Fengguang
2011-11-21 9:18 ` Wu Fengguang
2011-11-21 9:18 ` Wu Fengguang
2011-11-21 10:00 ` Christoph Hellwig
2011-11-21 10:00 ` Christoph Hellwig
2011-11-21 11:24 ` Wu Fengguang
2011-11-21 11:24 ` Wu Fengguang
2011-11-21 12:47 ` Andi Kleen
2011-11-21 12:47 ` Andi Kleen
2011-11-21 14:46 ` Jeff Moyer
2011-11-21 14:46 ` Jeff Moyer
2011-11-21 14:46 ` Jeff Moyer
2011-11-21 22:52 ` Andrew Morton
2011-11-21 22:52 ` Andrew Morton
2011-11-21 22:52 ` Andrew Morton
2011-11-22 14:23 ` Jeff Moyer
2011-11-22 14:23 ` Jeff Moyer
2011-11-22 14:23 ` Jeff Moyer
2011-11-23 12:18 ` Wu Fengguang
2011-11-23 12:18 ` Wu Fengguang
2011-11-21 9:18 ` [PATCH 2/8] readahead: make default readahead size a kernel parameter Wu Fengguang
2011-11-21 9:18 ` Wu Fengguang
2011-11-21 9:18 ` Wu Fengguang
2011-11-21 10:01 ` Christoph Hellwig
2011-11-21 10:01 ` Christoph Hellwig
2011-11-21 11:35 ` Wu Fengguang
2011-11-21 11:35 ` Wu Fengguang
2011-11-24 22:28 ` Jan Kara
2011-11-24 22:28 ` Jan Kara
2011-11-25 0:36 ` Dave Chinner
2011-11-25 0:36 ` Dave Chinner
2011-11-28 2:39 ` Wu Fengguang
2011-11-28 2:39 ` Wu Fengguang
2011-11-30 13:04 ` Christian Ehrhardt
2011-11-30 13:04 ` Christian Ehrhardt
2011-11-30 13:04 ` Christian Ehrhardt
2011-11-30 13:29 ` Wu Fengguang
2011-11-30 13:29 ` Wu Fengguang
2011-11-30 13:29 ` Wu Fengguang
2011-11-30 16:09 ` Jan Kara
2011-11-30 16:09 ` Jan Kara
2011-11-21 13:16 ` Namhyung Kim
2011-11-21 13:16 ` Namhyung Kim
2011-11-21 13:24 ` Wu Fengguang
2011-11-21 13:24 ` Wu Fengguang
2011-11-21 9:18 ` [PATCH 3/8] readahead: replace ra->mmap_miss with ra->ra_flags Wu Fengguang
2011-11-21 9:18 ` Wu Fengguang
2011-11-21 9:18 ` Wu Fengguang
2011-11-21 11:04 ` Steven Whitehouse
2011-11-21 11:04 ` Steven Whitehouse
2011-11-21 11:42 ` Wu Fengguang
2011-11-21 11:42 ` Wu Fengguang
2011-11-21 23:01 ` Andrew Morton
2011-11-21 23:01 ` Andrew Morton
2011-11-21 23:01 ` Andrew Morton
2011-11-23 12:47 ` Wu Fengguang
2011-11-23 12:47 ` Wu Fengguang
2011-11-23 20:31 ` Andrew Morton
2011-11-23 20:31 ` Andrew Morton
2011-11-29 3:42 ` Wu Fengguang
2011-11-29 3:42 ` Wu Fengguang
2011-11-21 9:18 ` [PATCH 4/8] readahead: record readahead patterns Wu Fengguang
2011-11-21 9:18 ` Wu Fengguang
2011-11-21 9:18 ` Wu Fengguang
2011-11-21 23:19 ` Andrew Morton
2011-11-21 23:19 ` Andrew Morton
2011-11-21 23:19 ` Andrew Morton
2011-11-29 2:40 ` Wu Fengguang
2011-11-29 2:40 ` Wu Fengguang
2011-11-21 9:18 ` [PATCH 5/8] readahead: add /debug/readahead/stats Wu Fengguang
2011-11-21 9:18 ` Wu Fengguang
2011-11-21 9:18 ` Wu Fengguang
2011-11-21 14:17 ` Andi Kleen
2011-11-21 14:17 ` Andi Kleen
2011-11-22 14:14 ` Wu Fengguang
2011-11-22 14:14 ` Wu Fengguang
2011-11-21 23:29 ` Andrew Morton
2011-11-21 23:29 ` Andrew Morton
2011-11-21 23:32 ` Andi Kleen [this message]
2011-11-21 23:32 ` Andi Kleen
2011-11-29 3:23 ` Wu Fengguang
2011-11-29 3:23 ` Wu Fengguang
2011-11-29 4:49 ` Andrew Morton
2011-11-29 4:49 ` Andrew Morton
2011-11-29 6:41 ` Wu Fengguang
2011-11-29 6:41 ` Wu Fengguang
2011-11-29 12:29 ` Wu Fengguang
2011-11-29 12:29 ` Wu Fengguang
2011-11-21 9:18 ` [PATCH 6/8] readahead: add debug tracing event Wu Fengguang
2011-11-21 9:18 ` Wu Fengguang
2011-11-21 9:18 ` Wu Fengguang
2011-11-21 14:01 ` Steven Rostedt
2011-11-21 14:01 ` Steven Rostedt
2011-11-21 9:18 ` [PATCH 7/8] readahead: basic support for backwards prefetching Wu Fengguang
2011-11-21 9:18 ` Wu Fengguang
2011-11-21 9:18 ` Wu Fengguang
2011-11-21 23:33 ` Andrew Morton
2011-11-21 23:33 ` Andrew Morton
2011-11-21 23:33 ` Andrew Morton
2011-11-29 3:08 ` Wu Fengguang
2011-11-29 3:08 ` Wu Fengguang
2011-11-21 9:18 ` [PATCH 8/8] readahead: dont do start-of-file readahead after lseek() Wu Fengguang
2011-11-21 9:18 ` Wu Fengguang
2011-11-21 9:18 ` Wu Fengguang
2011-11-21 23:36 ` Andrew Morton
2011-11-21 23:36 ` Andrew Morton
2011-11-21 23:36 ` Andrew Morton
2011-11-22 14:18 ` Wu Fengguang
2011-11-22 14:18 ` Wu Fengguang
2011-11-21 9:56 ` [PATCH 0/8] readahead stats/tracing, backwards prefetching and more Christoph Hellwig
2011-11-21 9:56 ` Christoph Hellwig
2011-11-21 12:00 ` Wu Fengguang
2011-11-21 12:00 ` Wu Fengguang
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20111121233255.GF24062@one.firstfloor.org \
--to=andi@firstfloor.org \
--cc=a.p.zijlstra@chello.nl \
--cc=akpm@linux-foundation.org \
--cc=fengguang.wu@intel.com \
--cc=jens.axboe@oracle.com \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mingo@elte.hu \
--cc=riel@redhat.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.