From nobody Sat May 11 16:12:50 2024 Delivered-To: importer@patchew.org Received-SPF: pass (zoho.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zohomail.com; spf=pass (zoho.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail(p=none dis=none) header.from=redhat.com ARC-Seal: i=1; a=rsa-sha256; t=1561907573; cv=none; d=zoho.com; s=zohoarc; b=awogZN7gKtzEoSeGsQZ5cpvyqlz2KUltZpOtcy1FTlfxxlnaQa8us8q94miCmMJmjzOY3pMmJknF1YB9GKAIC2/UmkBOSXB4guAYCePM77PkFbHKsF+8WTgeTrnDNXRx2LMA7sCHBybYfEpLOf6x5gbSeqxCLKvFkVAEU6PA2f8= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zoho.com; s=zohoarc; t=1561907573; h=Cc:Date:From:In-Reply-To:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:Message-ID:References:Sender:Subject:To:ARC-Authentication-Results; bh=cdPE8H+52YoX3GoRJBznE9qzvv/XVjBWqfN3ccAXjU4=; b=do8G/NUHFRZ6DOK4YHZnr3dPMG0OpTNdIEiaCjcdgUEH2xPTx6ND0NhlDgqB2VYU9U5GXqX4JVOTIrZpv7Mhr/KLyUSEFy56TCgQPF8bbmcq2J60ZkRqRCEfHKAJ78PniW+q0cvznB928e6VzH3d1nngVn18Du0/ubLvGU4oO4Y= ARC-Authentication-Results: i=1; mx.zoho.com; spf=pass (zoho.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail header.from= (p=none dis=none) header.from= Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1561907573175426.8835490259771; Sun, 30 Jun 2019 08:12:53 -0700 (PDT) Received: from localhost ([::1]:45146 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hhbVc-000747-7W for importer@patchew.org; Sun, 30 Jun 2019 11:12:52 -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+importer=patchew.org@nongnu.org Sender: "Qemu-devel" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" 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 Reviewed-by: Eric Blake Reviewed-by: Stefan Hajnoczi --- 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 =3D NULL; } =20 -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 =3D 0; - short max_sectors =3D 0; - if (bs->sg && ioctl(fd, BLKSECTGET, &max_bytes) =3D=3D 0) { + + if (ioctl(fd, BLKSECTGET, &max_bytes) =3D=3D 0) { return max_bytes; - } else if (!bs->sg && ioctl(fd, BLKSECTGET, &max_sectors) =3D=3D 0) { - return max_sectors << BDRV_SECTOR_BITS; } else { return -errno; } @@ -1055,7 +1053,7 @@ static int hdev_get_max_transfer_length(BlockDriverSt= ate *bs, int fd) #endif } =20 -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; =20 if (!fstat(s->fd, &st)) { - if (S_ISBLK(st.st_mode) || S_ISCHR(st.st_mode)) { - int ret =3D hdev_get_max_transfer_length(bs, s->fd); + if (bs->sg) { + int ret =3D sg_get_max_transfer_length(bs, s->fd); if (ret > 0 && ret <=3D BDRV_REQUEST_MAX_BYTES) { bs->bl.max_transfer =3D pow2floor(ret); } - ret =3D hdev_get_max_segments(&st); + ret =3D sg_get_max_segments(&st); if (ret > 0) { bs->bl.max_transfer =3D MIN(bs->bl.max_transfer, ret * getpagesize()); --=20 2.17.2