From: Peter Staubach <staubach@redhat.com>
To: Eric Dumazet <dada1@cosmosbay.com>
Cc: dipankar@in.ibm.com, "David S. Miller" <davem@davemloft.net>,
linux-kernel@vger.kernel.org, torvalds@osdl.org, akpm@osdl.org
Subject: Re: [PATCH] reorder struct files_struct
Date: Wed, 14 Sep 2005 17:35:55 -0400 [thread overview]
Message-ID: <432897BB.6040303@redhat.com> (raw)
In-Reply-To: <43289376.7050205@cosmosbay.com>
Eric Dumazet wrote:
> Hi
>
> Browsing (and using) the excellent RCU infrastructure for files that
> was adopted for 2.6.14-rc1, I noticed that the file_lock spinlock sit
> close to mostly read fields of 'struct files_struct'
>
> In SMP (and NUMA) environnements, each time a thread wants to open or
> close a file, it has to acquire the spinlock, thus invalidating the
> cache line containing this spinlock on other CPUS. So other threads
> doing read()/write()/... calls that use RCU to access the file table
> are going to ask further memory (possibly NUMA) transactions to read
> again this memory line.
>
> Please consider applying this patch. It moves the spinlock to another
> cache line, so that concurrent threads can share the cache line
> containing 'count' and 'fdt' fields.
How was the performance impact of this change measured?
Thanx...
ps
next prev parent reply other threads:[~2005-09-14 21:42 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-09-14 18:31 [PATCH]: Brown paper bag in fs/file.c? David S. Miller
2005-09-14 18:48 ` David S. Miller
2005-09-14 19:05 ` David S. Miller
2005-09-14 19:18 ` Dipankar Sarma
2005-09-14 19:57 ` David S. Miller
2005-09-14 20:15 ` Dipankar Sarma
2005-09-14 20:29 ` David S. Miller
2005-09-14 21:17 ` [PATCH] reorder struct files_struct Eric Dumazet
2005-09-14 21:35 ` Peter Staubach [this message]
2005-09-14 22:02 ` Dipankar Sarma
2005-09-14 22:17 ` Andrew Morton
2005-09-14 22:42 ` Eric Dumazet
2005-09-14 22:50 ` Dipankar Sarma
2005-09-14 23:19 ` Eric Dumazet
2005-09-15 4:54 ` Dipankar Sarma
2005-09-15 6:17 ` Eric Dumazet
2005-09-15 9:35 ` Dipankar Sarma
2005-09-15 17:11 ` Eric Dumazet
2005-09-15 21:06 ` [PATCH]: Brown paper bag in fs/file.c? David S. Miller
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