From: Ravikiran G Thirumalai <kiran@scalex86.org>
To: "Yu, Fenghua" <fenghua.yu@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
"Siddha, Suresh B" <suresh.b.siddha@intel.com>,
clameter@sgi.com, rmk@arm.linux.org.uk,
linux-kernel@vger.kernel.org, schwidefsky@de.ibm.com,
heiko.carstens@de.ibm.com
Subject: Re: [PATCH 1/2] Define new percpu interface for shared data -- version 3
Date: Wed, 23 May 2007 11:57:48 -0700 [thread overview]
Message-ID: <20070523185748.GA4072@localhost.localdomain> (raw)
In-Reply-To: <79E93560F4A5FD42BB769DAAF8BEF62A01AA8C77@scsmsx411.amr.corp.intel.com>
On Wed, May 23, 2007 at 11:26:53AM -0700, Yu, Fenghua wrote:
> > elements are cacheline aligned. And as such, this differentiates the
> local
> > only data and remotely accessed data cleanly.
>
> >OK, but could we please have a concise description of the impact
> >of these changes on kernel memory footprint? Increase or decrease?
> >And by approximately how much?
>
> Depending on how linker places percpu data, the patches could
> increase or decrease percpu section size. Data from 2.6.21-rc7-mm2:
>
> On x86 SMP, the section size is increased from 0x7768 to 0x790c.
> 1.3% increase.
>
> On X86-64 SMP, the size is decreased from 0x72d0 to 0x6540.
> 11.8% decrease.
>
> On X86-64 VSMP, the size is increased from 0x72d0 to 0x8340.
> 14.3% increase.
>
> On IA64 SMP, the size is decreased from 0x8370 to 0x7fc0.
> 2.8% decrease.
Has there been any measurable benefit yet due to tail padding?
It would also be interesting to check the wastage/savings on another large
cache architecture like S390 (which has a 256 byte cache line)
Thanks,
Kiran
next prev parent reply other threads:[~2007-05-23 18:57 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-05-22 12:47 is TIF_NOTIFY_RESUME used? Stephane Eranian
2007-05-22 16:02 ` Andrew Morton
2007-05-22 16:07 ` Stephane Eranian
2007-05-22 16:15 ` Andrew Morton
2007-05-22 22:51 ` Stephane Eranian
2007-05-22 23:02 ` Andrew Morton
2007-05-23 9:57 ` [PATCH] remove unused TIF_NOTIFY_RESUME flag Stephane Eranian
2007-05-22 18:20 ` [PATCH 1/2] Define new percpu interface for shared data -- version 3 Fenghua Yu
2007-05-23 17:49 ` Andrew Morton
2007-05-23 18:26 ` Yu, Fenghua
2007-05-23 18:57 ` Ravikiran G Thirumalai [this message]
2007-05-23 19:09 ` Yu, Fenghua
2007-05-23 19:20 ` Ravikiran G Thirumalai
2007-05-23 19:31 ` Andrew Morton
2007-05-23 21:13 ` Yu, Fenghua
2007-05-25 9:43 ` Russell King
2007-05-25 15:24 ` Yu, Fenghua
2007-05-24 9:03 ` Martin Schwidefsky
2007-05-24 10:16 ` Ravikiran G Thirumalai
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=20070523185748.GA4072@localhost.localdomain \
--to=kiran@scalex86.org \
--cc=akpm@linux-foundation.org \
--cc=clameter@sgi.com \
--cc=fenghua.yu@intel.com \
--cc=heiko.carstens@de.ibm.com \
--cc=linux-kernel@vger.kernel.org \
--cc=rmk@arm.linux.org.uk \
--cc=schwidefsky@de.ibm.com \
--cc=suresh.b.siddha@intel.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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox