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Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: References: <1966767.1673878095@warthog.procyon.org.uk> To: Linus Torvalds Cc: dhowells@redhat.com, Nicholas Piggin , Mateusz Guzik , linux-arch , Catalin Marinas , Will Deacon , Michael Ellerman , tony.luck@intel.com, viro@zeniv.linux.org.uk, linux-fsdevel@vger.kernel.org, Jan Glauber , linuxppc-dev , Linux ARM Subject: Re: Memory transaction instructions MIME-Version: 1.0 Content-ID: <2496130.1674032743.1@warthog.procyon.org.uk> Date: Wed, 18 Jan 2023 09:05:43 +0000 Message-ID: <2496131.1674032743@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 3.1 on 10.11.54.7 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230118_010559_108671_232ECE85 X-CRM114-Status: GOOD ( 18.98 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Linus Torvalds wrote: > And for the kernel, where we don't have bad locking, and where we > actually use fine-grained locks that are _near_ the data that we are > locking (the lockref of the dcache is obviously one example of that, > but the skbuff queue you mention is almost certainly exactly the same > situation): the lock is right by the data that the lock protects, and > the "shared lock cacheline" model simply does not work. You'll bounce > the data, and most likely you'll also touch the same lock cacheline > too. Yeah. The reason I was actually wondering about them was if it would be possible to avoid the requirement to disable interrupts/softirqs to, say, modify the skbuff queue. On some arches actually disabling irqs is quite a heavy operation (I think this is/was true on ppc64, for example; it certainly was on frv) and it was necessary to "emulate" the disablement. David _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel