From: "Hua Zhong" <hzhong@gmail.com>
To: "'Jens Axboe'" <axboe@suse.de>
Cc: <linux-kernel@vger.kernel.org>, <akpm@osdl.org>
Subject: RE: [PATCH] likely cleanup: revert unlikely in ll_back_merge_fn
Date: Tue, 25 Apr 2006 14:38:58 -0700 [thread overview]
Message-ID: <004d01c668b0$a9c79540$853d010a@nuitysystems.com> (raw)
In-Reply-To: <20060425183026.GR4102@suse.de>
It seems that new BIOs do not have BIO_SEG_VALID set. So when you do sequential IO, the IO being back-merged should always have not
had valid segments.
I ran bonnie++ and it shows the same thing.
> Well you'd want to optimize for the busy case, right, no
> point in optimizing for a more idle system.
>
> I'm not at all uninterested in this, I'd just like to see a
> more intelligent/controlled work load that actually stresses
> the io subsystem being profiled. If you have a not-so-busy
> system, you like don't do enough IO to trigger a lot of
> merges. Or maybe you do, and we just have a bug somewhere so
> that we unfortunately repeatedly recount segments.
>
> Care to run a simple io benchmark and profile that?
>
> --
> Jens Axboe
>
next prev parent reply other threads:[~2006-04-25 21:39 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-04-25 18:18 [PATCH] likely cleanup: revert unlikely in ll_back_merge_fn Hua Zhong
2006-04-25 18:30 ` Jens Axboe
2006-04-25 21:38 ` Hua Zhong [this message]
2006-04-26 5:20 ` Jens Axboe
2006-04-26 13:50 ` James Bottomley
2006-04-26 13:55 ` Jens Axboe
2006-04-26 14:24 ` James Bottomley
2006-04-27 14:39 ` Jens Axboe
2006-04-26 17:06 ` Hua Zhong
2006-04-30 19:25 ` Pavel Machek
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to='004d01c668b0$a9c79540$853d010a@nuitysystems.com' \
--to=hzhong@gmail.com \
--cc=akpm@osdl.org \
--cc=axboe@suse.de \
--cc=linux-kernel@vger.kernel.org \
/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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox