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=-16.6 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,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 02533C47082 for ; Thu, 3 Jun 2021 13:40:22 +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 BCA8D6121D for ; Thu, 3 Jun 2021 13:40:21 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BCA8D6121D 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]:60702 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lona8-0001P6-S6 for qemu-devel@archiver.kernel.org; Thu, 03 Jun 2021 09:40:20 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:50530) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lonXW-0002yF-80; Thu, 03 Jun 2021 09:37:38 -0400 Received: from mail-ed1-x52a.google.com ([2a00:1450:4864:20::52a]:40702) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1lonXU-00007m-LK; Thu, 03 Jun 2021 09:37:37 -0400 Received: by mail-ed1-x52a.google.com with SMTP id t3so7142808edc.7; Thu, 03 Jun 2021 06:37:35 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=7UAZdz5dQs7FMRLCi+6byKh+otX+O5RQQ9i+ZxcAI5g=; b=lrvGRs/lggaUJjrVirwjaik3/uHYyeye0NG36RG41WzzH747K12ANbXBlFIL3YCmBc 6PbS1tWA7nw4XKasH7vqrdmq3HbEX7ChgcV2cWvxm73D7NEUikRRQ/bHJXjIujmnKM+3 0PGrWb2aFLfuc9J/R9dc5sGqCbgtmW9kntN46PvTqeLCttI0iwmeM4TYWafgjNUpjDs6 heEsiiNE3Qqvgg0SuBGj+2stnbEcHAHNKcDQCn6U+AjZ6EX5TTLPCIXpxbmWS1s3xLsh ojGaK1eWyHpcptJU+eTgICXc4XN3v2/AVr7WPmtUjLWWI3D3AkbfM/vwAlQC/+8cmuG6 XEMA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:from:to:cc:subject:date:message-id :in-reply-to:references:mime-version:content-transfer-encoding; bh=7UAZdz5dQs7FMRLCi+6byKh+otX+O5RQQ9i+ZxcAI5g=; b=syPIgWzwFS3oTu4XgFJ3lm+DuaTws3es7RdVHLb/6Vg60n6c3JMhFyacQk3cInPrtw yKee+/jbU6qf+c666++TqnhtzCJgzYReALExe+wcRS4qIwOhCm96GjfSFDe74xvvvfHj jMLd8NQnIzMkRNw9zXtrNJvlEA7+giNdl0Fc7t1g3wtp/SQosfLu/9deRZsjDCSka1QS gVVzR5qcrkBwPat5yiCpFAtUDnDVod7rQ0N1wWh/JBzbB2Gu4zyaV7Qp6JCka5ihNGeu +zPWP37whgK5yUgMSZnSRDXFFrSAVImh+tFNOFkBzl7q7ykS2M3nPuw+HKu/DooaAQy5 dIww== X-Gm-Message-State: AOAM530NFrgx8lOZ95WXegHp4zJ5SuEFcNxFARjxYU/pb/yIwLbiDfkM a2t+5jfkZ3kIw+umb40cpMQUayKDG/dM2Q== X-Google-Smtp-Source: ABdhPJxtdMlhkmLdTI4RHhf8hCkvuwwhmA75nzvXjAmRKSl1sig5gL9TR6sLpSPoo2sTRjARKXfB/A== X-Received: by 2002:a50:eb08:: with SMTP id y8mr44358794edp.89.1622727454781; Thu, 03 Jun 2021 06:37:34 -0700 (PDT) Received: from localhost.localdomain ([2001:b07:6468:f312:c8dd:75d4:99ab:290a]) by smtp.gmail.com with ESMTPSA id e24sm1555369ejb.52.2021.06.03.06.37.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 03 Jun 2021 06:37:34 -0700 (PDT) From: Paolo Bonzini To: qemu-devel@nongnu.org Subject: [PATCH v3 4/7] file-posix: try BLKSECTGET on block devices too, do not round to power of 2 Date: Thu, 3 Jun 2021 15:37:19 +0200 Message-Id: <20210603133722.218465-5-pbonzini@redhat.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210603133722.218465-1-pbonzini@redhat.com> References: <20210603133722.218465-1-pbonzini@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=2a00:1450:4864:20::52a; envelope-from=paolo.bonzini@gmail.com; helo=mail-ed1-x52a.google.com X-Spam_score_int: -14 X-Spam_score: -1.5 X-Spam_bar: - X-Spam_report: (-1.5 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_FORGED_FROMDOMAIN=0.248, FREEMAIL_FROM=0.001, HEADER_FROM_DIFFERENT_DOMAINS=0.249, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=no 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: kwolf@redhat.com, qemu-block@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" bs->sg is only true for character devices, but block devices can also be used with scsi-block and scsi-generic. Unfortunately BLKSECTGET returns bytes in an int for /dev/sgN devices, and sectors in a short for block devices, so account for that in the code. The maximum transfer also need not be a power of 2 (for example I have seen disks with 1280 KiB maximum transfer) so there's no need to pass the result through pow2floor. This patch reintroduces the logic that was removed in commit 867eccfed8 ("file-posix: Use max transfer length/segment count only for SCSI passthrough", 2019-07-12). The removal was motivated by the performance regression when using a block device's max_transfer with kernel I/O; the new, separate max_hw_transfer limit avoids reintroducing the same regression. Signed-off-by: Paolo Bonzini --- block/file-posix.c | 40 ++++++++++++++++++++++------------------ 1 file changed, 22 insertions(+), 18 deletions(-) diff --git a/block/file-posix.c b/block/file-posix.c index f55f92d0f5..1439293f63 100644 --- a/block/file-posix.c +++ b/block/file-posix.c @@ -1149,22 +1149,27 @@ static void raw_reopen_abort(BDRVReopenState *state) s->reopen_state = NULL; } -static int sg_get_max_transfer_length(int fd) +static int hdev_get_max_hw_transfer(int fd, struct stat *st) { #ifdef BLKSECTGET - int max_bytes = 0; - - if (ioctl(fd, BLKSECTGET, &max_bytes) == 0) { - return max_bytes; + if (S_ISBLK(st->st_mode)) { + unsigned short max_sectors = 0; + if (ioctl(fd, BLKSECTGET, &max_sectors) == 0) { + return max_sectors * 512; + } } else { - return -errno; + int max_bytes = 0; + if (ioctl(fd, BLKSECTGET, &max_bytes) == 0) { + return max_bytes; + } } + return -errno; #else return -ENOSYS; #endif } -static int sg_get_max_segments(int fd) +static int hdev_get_max_segments(int fd, struct stat *st) { #ifdef CONFIG_LINUX char buf[32]; @@ -1173,12 +1178,6 @@ static int sg_get_max_segments(int fd) int ret; int sysfd = -1; long max_segments; - struct stat st; - - if (fstat(fd, &st)) { - ret = -errno; - goto out; - } if (S_ISCHR(st->st_mode)) { if (ioctl(fd, SG_GET_SG_TABLESIZE, &ret) == 0) { @@ -1192,7 +1191,7 @@ static int sg_get_max_segments(int fd) } sysfspath = g_strdup_printf("/sys/dev/block/%u:%u/queue/max_segments", - major(st.st_rdev), minor(st.st_rdev)); + major(st->st_rdev), minor(st->st_rdev)); sysfd = open(sysfspath, O_RDONLY); if (sysfd == -1) { ret = -errno; @@ -1229,15 +1228,20 @@ out: static void raw_refresh_limits(BlockDriverState *bs, Error **errp) { BDRVRawState *s = bs->opaque; + struct stat st; + + if (fstat(s->fd, &st)) { + return; + } - if (bs->sg) { - int ret = sg_get_max_transfer_length(s->fd); + if (bs->sg || S_ISBLK(st.st_mode)) { + int ret = hdev_get_max_hw_transfer(s->fd, &st); if (ret > 0 && ret <= BDRV_REQUEST_MAX_BYTES) { - bs->bl.max_hw_transfer = pow2floor(ret); + bs->bl.max_hw_transfer = ret; } - ret = sg_get_max_segments(s->fd); + ret = hdev_get_max_segments(s->fd, &st); if (ret > 0) { bs->bl.max_iov = ret; } -- 2.31.1