From patchwork Tue Jan 26 14:19:32 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Max Reitz X-Patchwork-Id: 12046817 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=-13.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 1D0A3C433DB for ; Tue, 26 Jan 2021 14:35:55 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id C8C2722D58 for ; Tue, 26 Jan 2021 14:35:54 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C8C2722D58 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:46696 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1l4PRh-00018D-O1 for qemu-devel@archiver.kernel.org; Tue, 26 Jan 2021 09:35:53 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:46584) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1l4PDb-0000AP-5v for qemu-devel@nongnu.org; Tue, 26 Jan 2021 09:21:19 -0500 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:37085) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1l4PDQ-00067U-PJ for qemu-devel@nongnu.org; Tue, 26 Jan 2021 09:21:18 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1611670866; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=28CVvT2G54J3FZYJjfNlAQL8l3qmUnDe43AQPKaBGkY=; b=ZsmFYRTfY6RR9C5hsCSrig3U6Lyx5JHAuYf2Lh5jhbsVNk6WK4s7JgRRde6ypp0YsVqDte mYCXVyS3NrCW/mL+6ludJ6geii0RTpUTrm9iR4es7YZ05yHa4GdyCadNUjdA8WgYGuUR29 WVyecyqwsbF0WW9jGNqoc3gj6AX6JPw= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-480-qRsQLkOfOTaCQfWlaXFRSw-1; Tue, 26 Jan 2021 09:21:02 -0500 X-MC-Unique: qRsQLkOfOTaCQfWlaXFRSw-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 7494F81451D; Tue, 26 Jan 2021 14:20:39 +0000 (UTC) Received: from localhost (ovpn-114-175.ams2.redhat.com [10.36.114.175]) by smtp.corp.redhat.com (Postfix) with ESMTPS id E4FD85D739; Tue, 26 Jan 2021 14:20:38 +0000 (UTC) From: Max Reitz To: qemu-block@nongnu.org Subject: [PULL 09/53] copy-on-read: skip non-guest reads if no copy needed Date: Tue, 26 Jan 2021 15:19:32 +0100 Message-Id: <20210126142016.806073-10-mreitz@redhat.com> In-Reply-To: <20210126142016.806073-1-mreitz@redhat.com> References: <20210126142016.806073-1-mreitz@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=mreitz@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Received-SPF: pass client-ip=63.128.21.124; envelope-from=mreitz@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -30 X-Spam_score: -3.1 X-Spam_bar: --- X-Spam_report: (-3.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.255, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kevin Wolf , Peter Maydell , qemu-devel@nongnu.org, Max Reitz Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" From: Andrey Shinkevich If the flag BDRV_REQ_PREFETCH was set, skip idling read/write operations in COR-driver. It can be taken into account for the COR-algorithms optimization. That check is being made during the block stream job by the moment. Add the BDRV_REQ_PREFETCH flag to the supported_read_flags of the COR-filter. block: Modify the comment for the flag BDRV_REQ_PREFETCH as we are going to use it alone and pass it to the COR-filter driver for further processing. Signed-off-by: Andrey Shinkevich Reviewed-by: Vladimir Sementsov-Ogievskiy Reviewed-by: Max Reitz Message-Id: <20201216061703.70908-9-vsementsov@virtuozzo.com> Signed-off-by: Max Reitz --- include/block/block.h | 8 +++++--- block/copy-on-read.c | 14 ++++++++++---- 2 files changed, 15 insertions(+), 7 deletions(-) diff --git a/include/block/block.h b/include/block/block.h index 127bdf3392..81fcaad5ac 100644 --- a/include/block/block.h +++ b/include/block/block.h @@ -72,9 +72,11 @@ typedef enum { BDRV_REQ_NO_FALLBACK = 0x100, /* - * BDRV_REQ_PREFETCH may be used only together with BDRV_REQ_COPY_ON_READ - * on read request and means that caller doesn't really need data to be - * written to qiov parameter which may be NULL. + * BDRV_REQ_PREFETCH makes sense only in the context of copy-on-read + * (i.e., together with the BDRV_REQ_COPY_ON_READ flag or when a COR + * filter is involved), in which case it signals that the COR operation + * need not read the data into memory (qiov) but only ensure they are + * copied to the top layer (i.e., that COR operation is done). */ BDRV_REQ_PREFETCH = 0x200, diff --git a/block/copy-on-read.c b/block/copy-on-read.c index 71560984f6..9cad9e1b8c 100644 --- a/block/copy-on-read.c +++ b/block/copy-on-read.c @@ -50,6 +50,8 @@ static int cor_open(BlockDriverState *bs, QDict *options, int flags, return -EINVAL; } + bs->supported_read_flags = BDRV_REQ_PREFETCH; + bs->supported_write_flags = BDRV_REQ_WRITE_UNCHANGED | (BDRV_REQ_FUA & bs->file->bs->supported_write_flags); @@ -172,10 +174,14 @@ static int coroutine_fn cor_co_preadv_part(BlockDriverState *bs, } } - ret = bdrv_co_preadv_part(bs->file, offset, n, qiov, qiov_offset, - local_flags); - if (ret < 0) { - return ret; + /* Skip if neither read nor write are needed */ + if ((local_flags & (BDRV_REQ_PREFETCH | BDRV_REQ_COPY_ON_READ)) != + BDRV_REQ_PREFETCH) { + ret = bdrv_co_preadv_part(bs->file, offset, n, qiov, qiov_offset, + local_flags); + if (ret < 0) { + return ret; + } } offset += n;