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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 0472ECF6D36 for ; Wed, 2 Oct 2024 15:15:48 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1sw148-0003bi-LD; Wed, 02 Oct 2024 11:15:01 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1sw145-0003bL-Uz for qemu-devel@nongnu.org; Wed, 02 Oct 2024 11:14:57 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1sw143-0004D5-Tk for qemu-devel@nongnu.org; Wed, 02 Oct 2024 11:14:57 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1727882094; 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=1impwNwNKeqViPVK8iwq1dhvRluXddYw0svnf2iE6PU=; b=NZsBOIHj1uLm/VQXjDhtAVGGM8PCd1l6oWR3ZepZuF5uoGELtg3Y1XxjitlPPwojjn3Xc9 qvOjRHBPOWOpYw9Mfzh8X0ALQHVfOdyycHJFH8HmaDDqcwXCjYcuWhbaCG+QB8j2/Oyzhg /JhaGWSR+O4R16rEGF6vxfYP2wRu1Vc= Received: from mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-235-ULWkyC8pN0SSqWn6GtsMew-1; Wed, 02 Oct 2024 11:14:50 -0400 X-MC-Unique: ULWkyC8pN0SSqWn6GtsMew-1 Received: from mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.40]) (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-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 74BBE1955F43; Wed, 2 Oct 2024 15:14:47 +0000 (UTC) Received: from blackfin.pond.sub.org (unknown [10.39.192.47]) by mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id ADA0F19560AD; Wed, 2 Oct 2024 15:14:46 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 0160721E6A28; Wed, 2 Oct 2024 17:14:42 +0200 (CEST) From: Markus Armbruster To: Vladimir Sementsov-Ogievskiy Cc: Eric Blake , qemu-devel@nongnu.org, kwolf@redhat.com, hreitz@redhat.com, berrange@redhat.com, qemu-block@nongnu.org, den@virtuozzo.com, andrey.drobyshev@virtuozzo.com, alexander.ivanov@virtuozzo.com Subject: Re: [PATCH 2/2] nbd/server: Allow users to adjust handshake limit in QMP In-Reply-To: (Vladimir Sementsov-Ogievskiy's message of "Wed, 2 Oct 2024 16:58:10 +0300") References: <20240809161828.1342831-4-eblake@redhat.com> <20240809161828.1342831-6-eblake@redhat.com> <87wmiqy5rl.fsf@pond.sub.org> Date: Wed, 02 Oct 2024 17:14:42 +0200 Message-ID: <87ed4ywn8d.fsf@pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 3.0 on 10.30.177.40 Received-SPF: pass client-ip=170.10.129.124; envelope-from=armbru@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -21 X-Spam_score: -2.2 X-Spam_bar: -- X-Spam_report: (-2.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.144, 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, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: 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 Vladimir Sementsov-Ogievskiy writes: > On 02.10.24 16:49, Markus Armbruster wrote: >> Eric Blake writes: >> >>> Although defaulting the handshake limit to 10 seconds was a nice QoI >>> change to weed out intentionally slow clients, it can interfere with >>> integration testing done with manual NBD_OPT commands over 'nbdsh >>> --opt-mode'. Expose a QMP knob 'handshake-max-secs' to allow the user >>> to alter the timeout away from the default. >>> >>> The parameter name here intentionally matches the spelling of the >>> constant added in commit fb1c2aaa98, and not the command-line spelling >>> added in the previous patch for qemu-nbd; that's because in QMP, >>> longer names serve as good self-documentation, and unlike the command >>> line, machines don't have problems generating longer spellings. >>> >>> Signed-off-by: Eric Blake [...] >> Are we confident we'll never need less than a full second? > > Hmm, recent "[PATCH v2] chardev: introduce 'reconnect-ms' and deprecate 'reconnect'" shows that at least sometimes second is not enough precision. > > Maybe, using milliseconds consistently for all relatively short time intervals in QAPI would be a good rule? Ideally, we'd use a single unit for time: nanoseconds. But we missed that chance long ago, and now are stuck with a mix of seconds, milliseconds, microseconds, and nanoseconds. I think a good rule is to pick the first from this list that will surely provide all the precision we'll ever need. In this case, milliseconds should do.