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=-8.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, MAILING_LIST_MULTI,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 A3E2FC433EF for ; Fri, 24 Sep 2021 10:15:29 +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 4794360EE4 for ; Fri, 24 Sep 2021 10:15:29 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 4794360EE4 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=nongnu.org Received: from localhost ([::1]:33264 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mTiEn-0001s3-GR for qemu-devel@archiver.kernel.org; Fri, 24 Sep 2021 06:15:25 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:44234) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mThw2-0000Fk-JZ for qemu-devel@nongnu.org; Fri, 24 Sep 2021 05:56:02 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:35732) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mThvz-0003Wt-GV for qemu-devel@nongnu.org; Fri, 24 Sep 2021 05:56:00 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1632477358; 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: in-reply-to:in-reply-to:references:references; bh=mHPyvTN2WsPm/vajElkeHZ9jKmh+Kq+DPuA1OylHVXk=; b=E3VMuK5qXC1ExE2OjJh/6MQrbOAlhLH25FOQW2IqvxMDmAhVsB6JfhOEzjmDnTIci90Mc0 swr+//31SsMQQpEBWdYHa8F4ICqvtGyGgBoQ3yVTz2p86PxBcVTwY78IoozEx2mMB1iwf0 e1nNC2h6XkQjtq7AVzbLTH8EidWvg0U= 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-559-iuL3K8jzMYun7AC2pfNxPg-1; Fri, 24 Sep 2021 05:55:57 -0400 X-MC-Unique: iuL3K8jzMYun7AC2pfNxPg-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 2F266362F8; Fri, 24 Sep 2021 09:55:56 +0000 (UTC) Received: from redhat.com (unknown [10.39.193.232]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 884AE5D9CA; Fri, 24 Sep 2021 09:55:52 +0000 (UTC) Date: Fri, 24 Sep 2021 11:55:51 +0200 From: Kevin Wolf To: Paolo Bonzini Subject: Re: [PATCH] block: introduce max_hw_iov for use in scsi-generic Message-ID: References: <20210923130436.1187591-1-pbonzini@redhat.com> MIME-Version: 1.0 In-Reply-To: <20210923130436.1187591-1-pbonzini@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=kwolf@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Received-SPF: pass client-ip=216.205.24.124; envelope-from=kwolf@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -42 X-Spam_score: -4.3 X-Spam_bar: ---- X-Spam_report: (-4.3 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1.473, 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_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham 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: Halil Pasic , Hanna Reitz , qemu-devel@nongnu.org, qemu-block@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Am 23.09.2021 um 15:04 hat Paolo Bonzini geschrieben: > Linux limits the size of iovecs to 1024 (UIO_MAXIOV in the kernel > sources, IOV_MAX in POSIX). Because of this, on some host adapters > requests with many iovecs are rejected with -EINVAL by the > io_submit() or readv()/writev() system calls. > > In fact, the same limit applies to SG_IO as well. To fix both the > EINVAL and the possible performance issues from using fewer iovecs > than allowed by Linux (some HBAs have max_segments as low as 128), > introduce a separate entry in BlockLimits to hold the max_segments > value from sysfs. This new limit is used only for SG_IO and clamped > to bs->bl.max_iov anyway, just like max_hw_transfer is clamped to > bs->bl.max_transfer. > > Reported-by: Halil Pasic > Cc: Hanna Reitz > Cc: Kevin Wolf > Cc: qemu-block@nongnu.org > Fixes: 18473467d5 ("file-posix: try BLKSECTGET on block devices too, do not round to power of 2", 2021-06-25) > Signed-off-by: Paolo Bonzini Thanks, applied to the block branch. Kevin