From: "Luck, Tony" <tony.luck@intel.com>
To: Petr Tesarik <ptesarik@suse.cz>
CC: "linux-ia64@vger.kernel.org" <linux-ia64@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Hedi Berriche <hedi@sgi.com>
Date: Fri, 27 Aug 2010 14:11:55 -0700
Subject: RE: Serious problem with ticket spinlocks on ia64
Thread-Topic: Serious problem with ticket spinlocks on ia64
Thread-Index: ActGK0PzUhFgckTtQg2dPIrcwTwA8wAANvww
Message-ID: <987664A83D2D224EAE907B061CE93D53015D91D45F@orsmsx505.amr.corp.intel.com>
References: <201008271537.35709.ptesarik@suse.cz>
 <987664A83D2D224EAE907B061CE93D53015D91D029@orsmsx505.amr.corp.intel.com>
 <987664A83D2D224EAE907B061CE93D53015D91D3B7@orsmsx505.amr.corp.intel.com>
 <201008272303.34228.ptesarik@suse.cz>
In-Reply-To: <201008272303.34228.ptesarik@suse.cz>
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> One more idea. The wrap-around case is the only one when the high word is 
> modified. This is in fact the only case when the fetchadd.acq competes with 
> the st2.rel about the actual contents of that location. I don't know if it 
> matters...

I pondered that for a while - but I have difficulty believing that
fetchadd looks at which bits changed and only writes back the bytes
that did.

-Tony
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