Date: Thu, 22 Mar 2001 20:05:04 +0200 From: Mark Murray <mark@grondar.za> To: Tony Finch <dot@dotat.at> Cc: freebsd-smp@FreeBSD.ORG Subject: Re: Locked data-structures and delayed writes. Message-ID: <200103221803.f2MI3tf50897@gratis.grondar.za> In-Reply-To: <E14g6vW-00077j-00@hand.dotat.at> ; from Tony Finch <dot@dotat.at> "Thu, 22 Mar 2001 15:23:02 GMT." References: <E14g6vW-00077j-00@hand.dotat.at>
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> Anyway, the question at hand is what happens if two threads on > different CPUs are accessing the same locked data structure when the > CPU delays writes to RAM, i.e. > > acquire_lock(s); > modify(s); > release_lock(s); > > Things are very broken if the write can be delayed until after the > lock is released. What prevents that? "man atomic", and look at the "acquire" and "release" memory barriers. M -- Mark Murray Warning: this .sig is umop ap!sdn To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-smp" in the body of the message
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