lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:	Fri, 23 Jan 2009 23:49:12 -0800
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Jan Kara <jack@...e.cz>
Cc:	linux-kernel@...r.kernel.org, linux-ext4@...r.kernel.org,
	linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH 01/11] quota: Improve locking

On Fri, 16 Jan 2009 19:08:09 +0100 Jan Kara <jack@...e.cz> wrote:

>  static DEFINE_SPINLOCK(dq_list_lock);
> +static DEFINE_SPINLOCK(dq_state_lock);
>  DEFINE_SPINLOCK(dq_data_lock);

The chances are very good that two or even three of these locks will
all get placed into the same cacheline in main memory.  The effects
will be quite bad if different CPUs (or, worse, different nodes) are
taking these locks.

For single, kernel-wide locks like these I think we should almost
always pad out to a cacheline.

With __cacheline_aligned_in_smp, rather than __cacheline_aligned. 
Because spinlocks do take space even in uniprocessor builds.

There are probably lots of existing locks which should be converted.
--
To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Powered by blists - more mailing lists