From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 99ED86453 for ; Tue, 22 Mar 2022 21:43:09 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 62FC5C340EC; Tue, 22 Mar 2022 21:43:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1647985389; bh=2fw4V34BMaBWwfa8lGQogtWOuNUo51fHy2VVhad5FVo=; h=Date:To:From:In-Reply-To:Subject:From; b=D7QK0v64JEml4OOpBVivrX3z4qSiP2SDe5UdQuX3UlhEiMIHfQPkkgU4uAJB8jteg sZ4NAuP5Um3Dm43Lb3SkTtv57rTWTycCqbYmn8JFKuny/gNuIXoRX/ep8FiUsc/plw gYt3rdYhPPhssQf7sBV2MS9moa43MVB9DbfnMhpk= Date: Tue, 22 Mar 2022 14:43:08 -0700 To: peterz@infradead.org,mgorman@suse.de,andreyknvl@gmail.com,pcc@google.com,akpm@linux-foundation.org,patches@lists.linux.dev,linux-mm@kvack.org,mm-commits@vger.kernel.org,torvalds@linux-foundation.org,akpm@linux-foundation.org From: Andrew Morton In-Reply-To: <20220322143803.04a5e59a07e48284f196a2f9@linux-foundation.org> Subject: [patch 091/227] mm/mmzone.c: use try_cmpxchg() in page_cpupid_xchg_last() Message-Id: <20220322214309.62FC5C340EC@smtp.kernel.org> Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: From: Peter Collingbourne Subject: mm/mmzone.c: use try_cmpxchg() in page_cpupid_xchg_last() This will let us avoid an additional read from page->flags when retrying the compare-exchange on some architectures. Link: https://lkml.kernel.org/r/20220120011200.1322836-1-pcc@google.com Link: https://linux-review.googlesource.com/id/I2e1f5b5b080ac9c4e0eb7f98768dba6fd7821693 Signed-off-by: Peter Collingbourne Suggested-by: Peter Zijlstra Cc: Andrey Konovalov Cc: Mel Gorman Signed-off-by: Andrew Morton --- mm/mmzone.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) --- a/mm/mmzone.c~mm-mmzonec-use-try_cmpxchg-in-page_cpupid_xchg_last +++ a/mm/mmzone.c @@ -89,13 +89,14 @@ int page_cpupid_xchg_last(struct page *p unsigned long old_flags, flags; int last_cpupid; + old_flags = READ_ONCE(page->flags); do { - old_flags = flags = page->flags; - last_cpupid = page_cpupid_last(page); + flags = old_flags; + last_cpupid = (flags >> LAST_CPUPID_PGSHIFT) & LAST_CPUPID_MASK; flags &= ~(LAST_CPUPID_MASK << LAST_CPUPID_PGSHIFT); flags |= (cpupid & LAST_CPUPID_MASK) << LAST_CPUPID_PGSHIFT; - } while (unlikely(cmpxchg(&page->flags, old_flags, flags) != old_flags)); + } while (unlikely(!try_cmpxchg(&page->flags, &old_flags, flags))); return last_cpupid; } _ From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id DA0F6C433FE for ; Tue, 22 Mar 2022 21:43:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236119AbiCVVox (ORCPT ); Tue, 22 Mar 2022 17:44:53 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51718 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236243AbiCVVol (ORCPT ); Tue, 22 Mar 2022 17:44:41 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4E4ED12771 for ; Tue, 22 Mar 2022 14:43:12 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id AA80CB81DAD for ; Tue, 22 Mar 2022 21:43:10 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 62FC5C340EC; Tue, 22 Mar 2022 21:43:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1647985389; bh=2fw4V34BMaBWwfa8lGQogtWOuNUo51fHy2VVhad5FVo=; h=Date:To:From:In-Reply-To:Subject:From; b=D7QK0v64JEml4OOpBVivrX3z4qSiP2SDe5UdQuX3UlhEiMIHfQPkkgU4uAJB8jteg sZ4NAuP5Um3Dm43Lb3SkTtv57rTWTycCqbYmn8JFKuny/gNuIXoRX/ep8FiUsc/plw gYt3rdYhPPhssQf7sBV2MS9moa43MVB9DbfnMhpk= Date: Tue, 22 Mar 2022 14:43:08 -0700 To: peterz@infradead.org, mgorman@suse.de, andreyknvl@gmail.com, pcc@google.com, akpm@linux-foundation.org, patches@lists.linux.dev, linux-mm@kvack.org, mm-commits@vger.kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org From: Andrew Morton In-Reply-To: <20220322143803.04a5e59a07e48284f196a2f9@linux-foundation.org> Subject: [patch 091/227] mm/mmzone.c: use try_cmpxchg() in page_cpupid_xchg_last() Message-Id: <20220322214309.62FC5C340EC@smtp.kernel.org> Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org From: Peter Collingbourne Subject: mm/mmzone.c: use try_cmpxchg() in page_cpupid_xchg_last() This will let us avoid an additional read from page->flags when retrying the compare-exchange on some architectures. Link: https://lkml.kernel.org/r/20220120011200.1322836-1-pcc@google.com Link: https://linux-review.googlesource.com/id/I2e1f5b5b080ac9c4e0eb7f98768dba6fd7821693 Signed-off-by: Peter Collingbourne Suggested-by: Peter Zijlstra Cc: Andrey Konovalov Cc: Mel Gorman Signed-off-by: Andrew Morton --- mm/mmzone.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) --- a/mm/mmzone.c~mm-mmzonec-use-try_cmpxchg-in-page_cpupid_xchg_last +++ a/mm/mmzone.c @@ -89,13 +89,14 @@ int page_cpupid_xchg_last(struct page *p unsigned long old_flags, flags; int last_cpupid; + old_flags = READ_ONCE(page->flags); do { - old_flags = flags = page->flags; - last_cpupid = page_cpupid_last(page); + flags = old_flags; + last_cpupid = (flags >> LAST_CPUPID_PGSHIFT) & LAST_CPUPID_MASK; flags &= ~(LAST_CPUPID_MASK << LAST_CPUPID_PGSHIFT); flags |= (cpupid & LAST_CPUPID_MASK) << LAST_CPUPID_PGSHIFT; - } while (unlikely(cmpxchg(&page->flags, old_flags, flags) != old_flags)); + } while (unlikely(!try_cmpxchg(&page->flags, &old_flags, flags))); return last_cpupid; } _