From: Jan Kara <jack@suse.cz>
To: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
Cc: Jan Kara <jack@suse.cz>,
Andrew Morton <akpm@linux-foundation.org>,
Fengguang Wu <fengguang.wu@intel.com>,
David Cohen <david.a.cohen@linux.intel.com>,
Al Viro <viro@zeniv.linux.org.uk>,
Damien Ramonda <damien.ramonda@intel.com>,
rientjes@google.com, Linus <torvalds@linux-foundation.org>,
nacc@linux.vnet.ibm.com, linux-mm@kvack.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH V6 ] mm readahead: Fix readahead fail for memoryless cpu and limit readahead pages
Date: Tue, 18 Feb 2014 13:04:30 +0100 [thread overview]
Message-ID: <20140218120430.GC29660@quack.suse.cz> (raw)
In-Reply-To: <53034C66.90707@linux.vnet.ibm.com>
On Tue 18-02-14 17:34:54, Raghavendra K T wrote:
> On 02/18/2014 03:19 PM, Jan Kara wrote:
> >On Tue 18-02-14 12:55:38, Raghavendra K T wrote:
> >>Currently max_sane_readahead() returns zero on the cpu having no local memory node
> >>which leads to readahead failure. Fix the readahead failure by returning
> >>minimum of (requested pages, 512). Users running application on a memory-less cpu
> >>which needs readahead such as streaming application see considerable boost in the
> >>performance.
> >>
> >>Result:
> >>fadvise experiment with FADV_WILLNEED on a PPC machine having memoryless CPU
> >>with 1GB testfile ( 12 iterations) yielded around 46.66% improvement.
> >>
> >>fadvise experiment with FADV_WILLNEED on a x240 machine with 1GB testfile
> >>32GB* 4G RAM numa machine ( 12 iterations) showed no impact on the normal
> >>NUMA cases w/ patch.
> > Can you try one more thing please? Compare startup time of some big
> >executable (Firefox or LibreOffice come to my mind) for the patched and
> >normal kernel on a machine which wasn't hit by this NUMA issue. And don't
> >forget to do "echo 3 >/proc/sys/vm/drop_caches" before each test to flush
> >the caches. If this doesn't show significant differences, I'm OK with the
> >patch.
> >
>
> Thanks Honza, I checked with firefox (starting to particular point)..
> I do not see any difference. Both the case took around 14sec.
Good. You can add my:
Acked-by: Jan Kara <jack@suse.cz>
> ( some time it is even faster.. may be because we do not do free
> page calculation?. )
Hardly, that calculation is just a tiny amount of CPU time in the
startup of the application. If there is really a significant difference, it
might be because we don't preload stuff which isn't used in the end.
Honza
--
Jan Kara <jack@suse.cz>
SUSE Labs, CR
--
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/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2014-02-18 12:04 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-02-18 7:25 [PATCH V6 ] mm readahead: Fix readahead fail for memoryless cpu and limit readahead pages Raghavendra K T
2014-02-18 9:49 ` Jan Kara
2014-02-18 12:04 ` Raghavendra K T
2014-02-18 12:04 ` Jan Kara [this message]
2014-03-17 2:07 ` Madper Xie
2014-03-18 7:13 ` Raghavendra K T
2014-02-18 22:23 ` David Rientjes
2014-02-18 22:38 ` Andrew Morton
2014-02-18 22:46 ` David Rientjes
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=20140218120430.GC29660@quack.suse.cz \
--to=jack@suse.cz \
--cc=akpm@linux-foundation.org \
--cc=damien.ramonda@intel.com \
--cc=david.a.cohen@linux.intel.com \
--cc=fengguang.wu@intel.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=nacc@linux.vnet.ibm.com \
--cc=raghavendra.kt@linux.vnet.ibm.com \
--cc=rientjes@google.com \
--cc=torvalds@linux-foundation.org \
--cc=viro@zeniv.linux.org.uk \
/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;
as well as URLs for NNTP newsgroup(s).