From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Zijlstra Subject: Re: [RFC PATCH 7/7] lazy tlb: shoot lazies, a non-refcounting lazy tlb option Date: Tue, 14 Jul 2020 15:23:41 +0200 Message-ID: <20200714132341.GY10769@hirez.programming.kicks-ass.net> References: <1594708054.04iuyxuyb5.astroid@bobo.none> <6D3D1346-DB1E-43EB-812A-184918CCC16A@amacapital.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43912 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727858AbgGNNXy (ORCPT ); Tue, 14 Jul 2020 09:23:54 -0400 Content-Disposition: inline In-Reply-To: <6D3D1346-DB1E-43EB-812A-184918CCC16A@amacapital.net> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Andy Lutomirski Cc: Nicholas Piggin , Anton Blanchard , Arnd Bergmann , linux-arch , LKML , Linux-MM , linuxppc-dev , Andy Lutomirski , Mathieu Desnoyers , X86 ML On Tue, Jul 14, 2020 at 05:46:05AM -0700, Andy Lutomirski wrote: > x86 has this exact problem. At least no more than 64*8 CPUs share the cache line :) I've seen patches for a 'sparse' bitmap to solve related problems. It's basically the same code, except it multiplies everything (size, bit-nr) by a constant to reduce the number of active bits per line. This sadly doesn't take topology into account, but reducing contention is still good ofcourse. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Tue, 14 Jul 2020 15:23:41 +0200 From: Peter Zijlstra Subject: Re: [RFC PATCH 7/7] lazy tlb: shoot lazies, a non-refcounting lazy tlb option Message-ID: <20200714132341.GY10769@hirez.programming.kicks-ass.net> References: <1594708054.04iuyxuyb5.astroid@bobo.none> <6D3D1346-DB1E-43EB-812A-184918CCC16A@amacapital.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <6D3D1346-DB1E-43EB-812A-184918CCC16A@amacapital.net> Sender: owner-linux-mm@kvack.org To: Andy Lutomirski Cc: Nicholas Piggin , Anton Blanchard , Arnd Bergmann , linux-arch , LKML , Linux-MM , linuxppc-dev , Andy Lutomirski , Mathieu Desnoyers , X86 ML List-ID: Message-ID: <20200714132341.aYRhrSxmw566u5gqL9offV8e0bA6qfqWd8VQd8Z43IE@z> On Tue, Jul 14, 2020 at 05:46:05AM -0700, Andy Lutomirski wrote: > x86 has this exact problem. At least no more than 64*8 CPUs share the cache line :) I've seen patches for a 'sparse' bitmap to solve related problems. It's basically the same code, except it multiplies everything (size, bit-nr) by a constant to reduce the number of active bits per line. This sadly doesn't take topology into account, but reducing contention is still good ofcourse.