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 X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BAFFCC4CECD for ; Mon, 16 Sep 2019 22:40:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 99E7F214AF for ; Mon, 16 Sep 2019 22:40:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388272AbfIPWkC (ORCPT ); Mon, 16 Sep 2019 18:40:02 -0400 Received: from mga02.intel.com ([134.134.136.20]:58611 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728232AbfIPWkC (ORCPT ); Mon, 16 Sep 2019 18:40:02 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga002.jf.intel.com ([10.7.209.21]) by orsmga101.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 16 Sep 2019 15:40:01 -0700 X-IronPort-AV: E=Sophos;i="5.64,514,1559545200"; d="scan'208";a="198493564" Received: from agluck-desk2.sc.intel.com ([10.3.52.68]) by orsmga002-auth.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 16 Sep 2019 15:40:01 -0700 From: Tony Luck To: Thomas Gleixner Cc: Peter Zijlstra , Fenghua Yu , Tony Luck , "Ingo Molnar" , "Borislav Petkov" , "H Peter Anvin" , "Andrew Morton" , "Dave Hansen" , "Paolo Bonzini" , "Radim Krcmar" , "Sai Praneeth Prakhya" , "Ravi V Shankar" , "linux-kernel" , "x86" Subject: [PATCH 2/3] drivers/net/b44: Align pwol_mask to unsigned long for better performance Date: Mon, 16 Sep 2019 15:39:57 -0700 Message-Id: <20190916223958.27048-3-tony.luck@intel.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190916223958.27048-1-tony.luck@intel.com> References: <1560897679-228028-1-git-send-email-fenghua.yu@intel.com> <20190916223958.27048-1-tony.luck@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Peter Zijlstra A bit in pwol_mask is set in b44_magic_pattern() by atomic set_bit(). But since pwol_mask is local and never exposed to concurrency, there is no need to set bit in pwol_mask atomically. set_bit() sets the bit in a single unsigned long location. Because pwol_mask may not be aligned to unsigned long, the location may cross two cache lines. On x86, accessing two cache lines in locked instruction in set_bit() is called split locked access and can cause overall performance degradation. So use non atomic __set_bit() to set pwol_mask bits. __set_bit() won't hit split lock issue on x86. Signed-off-by: Peter Zijlstra Signed-off-by: Fenghua Yu Signed-off-by: Tony Luck --- drivers/net/ethernet/broadcom/b44.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/net/ethernet/broadcom/b44.c b/drivers/net/ethernet/broadcom/b44.c index 97ab0dd25552..5738ab963dfb 100644 --- a/drivers/net/ethernet/broadcom/b44.c +++ b/drivers/net/ethernet/broadcom/b44.c @@ -1520,7 +1520,7 @@ static int b44_magic_pattern(u8 *macaddr, u8 *ppattern, u8 *pmask, int offset) memset(ppattern + offset, 0xff, magicsync); for (j = 0; j < magicsync; j++) - set_bit(len++, (unsigned long *) pmask); + __set_bit(len++, (unsigned long *)pmask); for (j = 0; j < B44_MAX_PATTERNS; j++) { if ((B44_PATTERN_SIZE - len) >= ETH_ALEN) @@ -1532,7 +1532,7 @@ static int b44_magic_pattern(u8 *macaddr, u8 *ppattern, u8 *pmask, int offset) for (k = 0; k< ethaddr_bytes; k++) { ppattern[offset + magicsync + (j * ETH_ALEN) + k] = macaddr[k]; - set_bit(len++, (unsigned long *) pmask); + __set_bit(len++, (unsigned long *)pmask); } } return len - 1; -- 2.20.1