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=-3.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,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 B889BC43142 for ; Thu, 2 Aug 2018 22:26:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7C8AA215EC for ; Thu, 2 Aug 2018 22:26:40 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7C8AA215EC Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732371AbeHCATt (ORCPT ); Thu, 2 Aug 2018 20:19:49 -0400 Received: from mail.kernel.org ([198.145.29.99]:35078 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732299AbeHCATr (ORCPT ); Thu, 2 Aug 2018 20:19:47 -0400 Received: from localhost.localdomain (c-98-220-238-81.hsd1.il.comcast.net [98.220.238.81]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 6CD00215E4; Thu, 2 Aug 2018 22:26:36 +0000 (UTC) From: Tom Zanussi To: linux-kernel@vger.kernel.org, linux-rt-users@vger.kernel.org Cc: rostedt@goodmis.org, tglx@linutronix.de, C.Emde@osadl.org, jkacur@redhat.com, bigeasy@linutronix.de, daniel.wagner@siemens.com, julia@ni.com, stable-rt@vger.kernel.org, Tom Zanussi Subject: [PATCH 09/15] squashfs: make use of local lock in multi_cpu decompressor Date: Thu, 2 Aug 2018 17:25:24 -0500 Message-Id: X-Mailer: git-send-email 2.14.1 In-Reply-To: References: In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Julia Cartwright Currently, the squashfs multi_cpu decompressor makes use of get_cpu_ptr()/put_cpu_ptr(), which unconditionally disable preemption during decompression. Because the workload is distributed across CPUs, all CPUs can observe a very high wakeup latency, which has been seen to be as much as 8000us. Convert this decompressor to make use of a local lock, which will allow execution of the decompressor with preemption-enabled, but also ensure concurrent accesses to the percpu compressor data on the local CPU will be serialized. Cc: stable-rt@vger.kernel.org Reported-by: Alexander Stein Tested-by: Alexander Stein Signed-off-by: Julia Cartwright Signed-off-by: Sebastian Andrzej Siewior (cherry picked from commit c160736542d7b3d67da32848d2f028b8e35730e5) Signed-off-by: Tom Zanussi --- fs/squashfs/decompressor_multi_percpu.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-) diff --git a/fs/squashfs/decompressor_multi_percpu.c b/fs/squashfs/decompressor_multi_percpu.c index 23a9c28ad8ea..6a73c4fa88e7 100644 --- a/fs/squashfs/decompressor_multi_percpu.c +++ b/fs/squashfs/decompressor_multi_percpu.c @@ -10,6 +10,7 @@ #include #include #include +#include #include "squashfs_fs.h" #include "squashfs_fs_sb.h" @@ -25,6 +26,8 @@ struct squashfs_stream { void *stream; }; +static DEFINE_LOCAL_IRQ_LOCK(stream_lock); + void *squashfs_decompressor_create(struct squashfs_sb_info *msblk, void *comp_opts) { @@ -79,10 +82,15 @@ int squashfs_decompress(struct squashfs_sb_info *msblk, struct buffer_head **bh, { struct squashfs_stream __percpu *percpu = (struct squashfs_stream __percpu *) msblk->stream; - struct squashfs_stream *stream = get_cpu_ptr(percpu); - int res = msblk->decompressor->decompress(msblk, stream->stream, bh, b, - offset, length, output); - put_cpu_ptr(stream); + struct squashfs_stream *stream; + int res; + + stream = get_locked_ptr(stream_lock, percpu); + + res = msblk->decompressor->decompress(msblk, stream->stream, bh, b, + offset, length, output); + + put_locked_ptr(stream_lock, stream); if (res < 0) ERROR("%s decompression failed, data probably corrupt\n", -- 2.14.1