From: David Miller <davem@davemloft.net>
To: dada1@cosmosbay.com
Cc: akpm@linux-foundation.org, a.p.zijlstra@chello.nl,
travis@sgi.com, linux-kernel@vger.kernel.org,
cl@linux-foundation.org, linux-ext4@vger.kernel.org
Subject: Re: [PATCH] percpu_counter: FBC_BATCH might be too big
Date: Fri, 05 Dec 2008 12:32:02 -0800 (PST) [thread overview]
Message-ID: <20081205.123202.98853955.davem@davemloft.net> (raw)
In-Reply-To: <4939513C.3090101@cosmosbay.com>
From: Eric Dumazet <dada1@cosmosbay.com>
Date: Fri, 05 Dec 2008 17:05:16 +0100
> For NR_CPUS >= 16 values, FBC_BATCH is 2*NR_CPUS
>
> Considering more and more distros are using high NR_CPUS values,
> it makes sense to use a more sensible value for FBC_BATCH.
>
> A sensible value is 2*num_online_cpus(), with a minimum value of 32
> (This minimum value helps branch prediction in __percpu_counter_add())
>
> We already have a hotcpu notifier, so we can adjust FBC_BATCH dynamically.
>
> Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
The downside is now we must load this value in these common
routines. But I think the gain outweights the loss so:
Acked-by: David S. Miller <davem@davemloft.net>
next prev parent reply other threads:[~2008-12-05 20:32 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-12-05 16:05 Eric Dumazet
2008-12-05 16:40 ` Peter Zijlstra
2008-12-05 20:32 ` David Miller [this message]
2008-12-07 9:25 ` [PATCH, take2] " Eric Dumazet
2008-12-07 17:09 ` Andrew Morton
2008-12-07 18:30 ` Eric Dumazet
2008-12-08 4:32 ` Andrew Morton
2008-12-08 8:05 ` [PATCH] percpu_counter: FBC_BATCH should be a variable Eric Dumazet
2008-12-08 8:19 ` Andrew Morton
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=20081205.123202.98853955.davem@davemloft.net \
--to=davem@davemloft.net \
--cc=a.p.zijlstra@chello.nl \
--cc=akpm@linux-foundation.org \
--cc=cl@linux-foundation.org \
--cc=dada1@cosmosbay.com \
--cc=linux-ext4@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=travis@sgi.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
Powered by JetHome