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 Received: from lists1p.gnu.org (lists1p.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 126C3C55167 for ; Fri, 31 Jul 2026 07:24:17 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists1p.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1wphau-0002An-Vf; Fri, 31 Jul 2026 03:23:49 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists1p.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1wphar-0002AS-Tx for qemu-devel@nongnu.org; Fri, 31 Jul 2026 03:23:46 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1wphaq-0007Xs-Fm for qemu-devel@nongnu.org; Fri, 31 Jul 2026 03:23:45 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1785482622; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=DFy5V3bT60WjqeV+MUGnBKA+v/q9X4Vi4mMPKW1zccA=; b=BfxN5Bv7/Rd8fJJqkG/bOJUOmTMGCklkAeQb2ix9h8XzV7Nn7LzrYDIYEfhLS1IkjWMYq7 7XY8vuVFCAihTEa+K59qtppCt7L1/TUKBocYLk5uZRgGSVng2SEmLSZAgZLFuQhvVWkD5J wPYRwvhNk4KevgNcCjGFzqa3JASt7J4= Received: from mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-44--REUL4s6PiaU1fVkaik3TA-1; Fri, 31 Jul 2026 03:23:39 -0400 X-MC-Unique: -REUL4s6PiaU1fVkaik3TA-1 X-Mimecast-MFC-AGG-ID: -REUL4s6PiaU1fVkaik3TA_1785482618 Received: from mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.111]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id DD6FA180036E; Fri, 31 Jul 2026 07:23:37 +0000 (UTC) Received: from blackfin.pond.sub.org (unknown [10.44.22.4]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 66089180044F; Fri, 31 Jul 2026 07:23:37 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id D6AF421E6920; Fri, 31 Jul 2026 09:23:34 +0200 (CEST) From: Markus Armbruster To: Zhang Chen Cc: qemu-devel , "Dr . David Alan Gilbert" , Eric Blake , "Michael S . Tsirkin" , Stefan Hajnoczi , Paolo Bonzini , Kevin Wolf , Jason Wang , Fam Zheng , Daniel P . =?utf-8?Q?Berrang=C3=A9?= Subject: Re: [RESEND PATCH V10 06/15] monitor: Update tracking iothread users with holder In-Reply-To: (Zhang Chen's message of "Fri, 31 Jul 2026 10:42:29 +0800") References: <20260716172108.87700-1-zhangckid@gmail.com> <20260716172108.87700-7-zhangckid@gmail.com> <87a4rkplof.fsf@pond.sub.org> Date: Fri, 31 Jul 2026 09:23:34 +0200 Message-ID: <87cxw3aah5.fsf@pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 Received-SPF: pass client-ip=170.10.133.124; envelope-from=armbru@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -36 X-Spam_score: -3.7 X-Spam_bar: --- X-Spam_report: (-3.7 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1.58, 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_PASS=-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: 2.1.29 Precedence: list List-Id: qemu development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Zhang Chen writes: > On Tue, Jul 21, 2026 at 8:33=E2=80=AFPM Markus Armbruster wrote: >> >> Zhang Chen writes: >> >> > Based on monitor QOM path tracking iothread users with holder. >> > Introduce the AioContext in the Monitor struct to avoid repeated calls= to >> > iothread_get_aio_context() and ensure symmetrical ref/unref during >> > monitor lifecycle. >> > >> > Signed-off-by: Zhang Chen >> >> Why are repeated calls bad? >> >> How would symmetry be lost? >> > > OK, will add detailed comments like this in the next version: > > Avoid repeated calls: Under the holder tracking model, fetching the > AioContext increments the IOThread refcount and registers holder metadata. > Dynamically querying it in helper functions (e.g., suspend, BH scheduling) > leads to redundant refcount churn. Right here, we still have AioContext *iothread_get_aio_context(IOThread *iothread) { return iothread->ctx; } and complicating code to avoid additional calls feels dubious. PATCH 14 changes it to AioContext *iothread_get_aio_context(IOThread *iothread, const IOThreadHolder *holder) { /* Add IOThreadHolder to the list */ iothread_ref(iothread, holder); return iothread->ctx; } Are you making this change in preparation of PATCH 14? > Ensure lifecycle symmetry: Storing AioContext in mon->ctx establishes a > strict 1-to-1 lifecycle pairing: a single iothread_ref_and_get_aio_contex= t() > in monitor_complete() matched by a single iothread_put_aio_context() > in monitor_cleanup(). > > Thanks > Chen