From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753559AbdJHVbK (ORCPT ); Sun, 8 Oct 2017 17:31:10 -0400 Received: from mail-by2nam01on0056.outbound.protection.outlook.com ([104.47.34.56]:27136 "EHLO NAM01-BY2-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751241AbdJHVbH (ORCPT ); Sun, 8 Oct 2017 17:31:07 -0400 Authentication-Results: spf=none (sender IP is ) smtp.mailfrom=Yuri.Norov@cavium.com; Date: Mon, 9 Oct 2017 00:30:52 +0300 From: Yury Norov To: Will Deacon Cc: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Jeremy.Linton@arm.com, peterz@infradead.org, mingo@redhat.com, longman@redhat.com, boqun.feng@gmail.com, paulmck@linux.vnet.ibm.com Subject: Re: [PATCH v2 0/5] Switch arm64 over to qrwlock Message-ID: <20171008213052.ojyxpr56d2ypscjy@yury-thinkpad> References: <1507296882-18721-1-git-send-email-will.deacon@arm.com> MIME-Version: 1.0 Content-Type: text/plain; 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I also respin the patch of Jan Glauber [1], and I also tried Jan's patch with patch 5 from this series. Numbers differ a lot from my previous measurements, but since that I changed working station and use qemu with the support of parallel threads. Spinlock Read-RW lock Write-RW lock Vanilla: 129804626 12340895 14716138 This series: 113718002 10982159 13068934 Jan patch: 117977108 11363462 13615449 Jan patch + #5: 121483176 11696728 13618967 The bottomline of discussion [1] was that queued locks are more effective when SoC has many CPUs. And 4 is not many. My measurement was made on the 4-CPU machine, and it seems it confirms that. Does it make sense to make queued locks default for many-CPU machines only? There were 2 preparing patches in the series: [PATCH 1/3] kernel/locking: #include in qrwlock and [PATCH 2/3] asm-generic: don't #include in qspinlock_types.h 1st patch is not needed anymore because Babu Moger submitted similar patch that is already in mainline: 9ab6055f95903 ("kernel/locking: Fix compile error with qrwlock.c"). Could you revisit second patch? [1] https://lkml.org/lkml/2017/5/3/330 Yury