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From: Dan Magenheimer <dan.magenheimer@oracle.com>
To: "Xen-Devel (E-mail)" <xen-devel@lists.xensource.com>
Subject: atomic counters larger than 24 bits?
Date: Thu, 26 Mar 2009 19:38:13 +0000 (GMT)	[thread overview]
Message-ID: <aa4cfdc9-285e-4ff0-8b51-c3de728135cd@default> (raw)

In tmem, I have some counters that I need to keep coherent,
preferably without a lock, so I'm using atomic_inc/dec etc.
However the comments in include/asm-x86/atomic.h say repeatedly
that the "useful range of an atomic_t is only 24 bits".

First, are the comments true in the xen implementation?
(I don't see any code that restricts them to anything less
than "int".)  If they ARE limited to 24 bits, what's the
recommended approach for larger atomic operations... or
do I just need to always use a lock?

Thanks,
Dan

             reply	other threads:[~2009-03-26 19:38 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-03-26 19:38 Dan Magenheimer [this message]
2009-03-26 23:26 ` atomic counters larger than 24 bits? Samuel Thibault
2009-03-27  8:52   ` Keir Fraser
2009-03-27 18:15 ` Jeremy Fitzhardinge

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