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=-3.5 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no 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 D794CC63777 for ; Thu, 26 Nov 2020 21:49:35 +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 42B8820B80 for ; Thu, 26 Nov 2020 21:49:35 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="YiTTrp1y" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 42B8820B80 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]:55480 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kiP8w-0001Cu-Eb for qemu-devel@archiver.kernel.org; Thu, 26 Nov 2020 16:49:34 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:35848) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kiP7y-0000LE-0G for qemu-devel@nongnu.org; Thu, 26 Nov 2020 16:48:34 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:52389) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1kiP7u-00056A-10 for qemu-devel@nongnu.org; Thu, 26 Nov 2020 16:48:33 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1606427307; 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=ILR0ZaTx5mpfsZHHqwJA193TbRWATvjIepa9NXwM4x4=; b=YiTTrp1yyLox4uBDr1SzBmVLn/qIZJYCDhhaePpYqTKTxkVV8XGISkCRowSAqu/AHKYyzt ZIoNIR11rfwE7E8XaZnAzhDDoX7VvSrOjQPA2tYYAYb/WskmeKJ7A+37rdAKc3/B7L0xd+ gB+6ahV25yT8pEAhar81eTb1mklQ0fQ= 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-589-sH2MNn6qN3S_Cv9zNi7i4A-1; Thu, 26 Nov 2020 16:48:26 -0500 X-MC-Unique: sH2MNn6qN3S_Cv9zNi7i4A-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 B24DE10073AB; Thu, 26 Nov 2020 21:48:24 +0000 (UTC) Received: from localhost (unknown [10.10.67.2]) by smtp.corp.redhat.com (Postfix) with ESMTP id 416B65D752; Thu, 26 Nov 2020 21:48:11 +0000 (UTC) Date: Thu, 26 Nov 2020 16:48:10 -0500 From: Eduardo Habkost To: Claudio Fontana Subject: Re: [PATCH v2 2/6] accel: accel_available() function Message-ID: <20201126214810.GR2271382@habkost.net> References: <20201125205636.3305257-1-ehabkost@redhat.com> <20201125205636.3305257-3-ehabkost@redhat.com> <12f82771-9db9-8fcd-ea25-736428d2650a@suse.de> <20201126133645.GG2271382@habkost.net> <8d90d611-6545-a478-1316-542dc5424b92@suse.de> <7df7713c-5125-9e41-3572-a476cad2946b@suse.de> MIME-Version: 1.0 In-Reply-To: <7df7713c-5125-9e41-3572-a476cad2946b@suse.de> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=ehabkost@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Received-SPF: pass client-ip=216.205.24.124; envelope-from=ehabkost@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=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: Thomas Huth , Richard Henderson , qemu-devel@nongnu.org, Roman Bolshakov , Gerd Hoffmann , Paolo Bonzini Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Thu, Nov 26, 2020 at 10:06:03PM +0100, Claudio Fontana wrote: > On 11/26/20 3:25 PM, Paolo Bonzini wrote: > > On 26/11/20 15:13, Claudio Fontana wrote: > >> One option I see is simply to document the behavior where > >> accel_available() is declared in accel.h (ie do not use in fast > >> path), as well as in accel_find() actually, so that both accel_find() > >> and accel_available() are avoided in fast path and avoid being called > >> frequently at runtime. > >> > >> Another option could be to remove the allocation completely, and use > >> for example accel_find(ACCEL_CLASS_NAME("tcg")), or another option > >> again would be to remove the allocation and use either a fixed buffer > >> + snprintf, or alloca -like builtin code to use the stack, ... > >> > >> Not a big deal, but with a general utility and short name like > >> accel_available(name) it might be tempting to use this more in the > >> future? > > > > I think it's just that the usecase is not that common. "Is this > > accelerator compiled in the binary" is not something you need after > > startup (or if querying the monitor). > > > > Paolo > > > > > > A script that repeatedly uses the QMP interface to query for > the status could generate fragmentation this way I think. Is this a problem? Today, execution of a "query-kvm" command calls g_malloc() 37 times. -- Eduardo