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=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 0B777C5B57E for ; Sun, 30 Jun 2019 15:12:32 +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 CDA3720665 for ; Sun, 30 Jun 2019 15:12:31 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CDA3720665 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]:45146 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hhbVH-000747-0Z for qemu-devel@archiver.kernel.org; Sun, 30 Jun 2019 11:12:31 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:33177) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hhbTh-00060v-5e for qemu-devel@nongnu.org; Sun, 30 Jun 2019 11:10:54 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hhbTf-0001sY-Vf for qemu-devel@nongnu.org; Sun, 30 Jun 2019 11:10:53 -0400 Received: from mx1.redhat.com ([209.132.183.28]:33620) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hhbTc-0000Tm-Ml; Sun, 30 Jun 2019 11:10:48 -0400 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 980A3C049589; Sun, 30 Jun 2019 15:09:02 +0000 (UTC) Received: from maximlenovopc.usersys.redhat.com (unknown [10.35.206.39]) by smtp.corp.redhat.com (Postfix) with ESMTP id C61901001B21; Sun, 30 Jun 2019 15:09:00 +0000 (UTC) From: Maxim Levitsky To: qemu-devel@nongnu.org Date: Sun, 30 Jun 2019 18:08:55 +0300 Message-Id: <20190630150855.1016-2-mlevitsk@redhat.com> In-Reply-To: <20190630150855.1016-1-mlevitsk@redhat.com> References: <20190630150855.1016-1-mlevitsk@redhat.com> X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.31]); Sun, 30 Jun 2019 15:09:02 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PATCH 1/1] raw-posix.c - use max transfer length / max segemnt count only for SCSI passthrough 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: Fam Zheng , Kevin Wolf , qemu-block@nongnu.org, Maxim Levitsky , John Ferlan , Max Reitz Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Regular block devices (/dev/sda*, /dev/nvme*, etc) interface is not limited by the underlying storage limits, but rather the kernel block layer takes care to split the requests that are too large/fragmented. Doing so allows us to have less overhead in qemu. Signed-off-by: Maxim Levitsky --- block/file-posix.c | 16 +++++++--------- 1 file changed, 7 insertions(+), 9 deletions(-) diff --git a/block/file-posix.c b/block/file-posix.c index ab05b51a66..66dad34f8a 100644 --- a/block/file-posix.c +++ b/block/file-posix.c @@ -1038,15 +1038,13 @@ static void raw_reopen_abort(BDRVReopenState *state) s->reopen_state = NULL; } -static int hdev_get_max_transfer_length(BlockDriverState *bs, int fd) +static int sg_get_max_transfer_length(BlockDriverState *bs, int fd) { #ifdef BLKSECTGET int max_bytes = 0; - short max_sectors = 0; - if (bs->sg && ioctl(fd, BLKSECTGET, &max_bytes) == 0) { + + if (ioctl(fd, BLKSECTGET, &max_bytes) == 0) { return max_bytes; - } else if (!bs->sg && ioctl(fd, BLKSECTGET, &max_sectors) == 0) { - return max_sectors << BDRV_SECTOR_BITS; } else { return -errno; } @@ -1055,7 +1053,7 @@ static int hdev_get_max_transfer_length(BlockDriverState *bs, int fd) #endif } -static int hdev_get_max_segments(const struct stat *st) +static int sg_get_max_segments(const struct stat *st) { #ifdef CONFIG_LINUX char buf[32]; @@ -1106,12 +1104,12 @@ static void raw_refresh_limits(BlockDriverState *bs, Error **errp) struct stat st; if (!fstat(s->fd, &st)) { - if (S_ISBLK(st.st_mode) || S_ISCHR(st.st_mode)) { - int ret = hdev_get_max_transfer_length(bs, s->fd); + if (bs->sg) { + int ret = sg_get_max_transfer_length(bs, s->fd); if (ret > 0 && ret <= BDRV_REQUEST_MAX_BYTES) { bs->bl.max_transfer = pow2floor(ret); } - ret = hdev_get_max_segments(&st); + ret = sg_get_max_segments(&st); if (ret > 0) { bs->bl.max_transfer = MIN(bs->bl.max_transfer, ret * getpagesize()); -- 2.17.2