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=-7.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 21DDCC47082 for ; Tue, 8 Jun 2021 12:29:47 +0000 (UTC) Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (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 C52CD61352 for ; Tue, 8 Jun 2021 12:29:46 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C52CD61352 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=tempfail smtp.mailfrom=linux-lvm-bounces@redhat.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1623155385; h=from:from:sender:sender:reply-to: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:list-id:list-help: list-unsubscribe:list-subscribe:list-post; bh=QLDr6MJYy7J34ZWCgLUz0r2wktRXdE2q7Gc80Jsdvw0=; b=hSjURG8+jWbCiwENb4rWeVR0HLlO5+3ks4X8UfF4POd0dbBs9RXK6AZvCcPn++kmh7rtc3 N3ZVulh4oero5N7An47LlVo/zJPFThuMlZMpzZduSkDWMmf6g6A18f3mgWbZaiHySRJCgm QGYyZRbudDIr0X8Rr3AKHbj5BSLrqGY= 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-46-_KhDWRG_N_Gk4mbX28jkRA-1; Tue, 08 Jun 2021 08:29:44 -0400 X-MC-Unique: _KhDWRG_N_Gk4mbX28jkRA-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id DE23F8B0BEA; Tue, 8 Jun 2021 12:29:28 +0000 (UTC) Received: from colo-mx.corp.redhat.com (colo-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.21]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 5708319C66; Tue, 8 Jun 2021 12:29:26 +0000 (UTC) Received: from lists01.pubmisc.prod.ext.phx2.redhat.com (lists01.pubmisc.prod.ext.phx2.redhat.com [10.5.19.33]) by colo-mx.corp.redhat.com (Postfix) with ESMTP id 778535F98A; Tue, 8 Jun 2021 12:29:11 +0000 (UTC) Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) by lists01.pubmisc.prod.ext.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id 158CT6iA029874 for ; Tue, 8 Jun 2021 08:29:06 -0400 Received: by smtp.corp.redhat.com (Postfix) id 4C5C38428A; Tue, 8 Jun 2021 12:29:06 +0000 (UTC) Received: from alatyr-rpi.brq.redhat.com (unknown [10.43.17.19]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 8E6CC70F79; Tue, 8 Jun 2021 12:29:04 +0000 (UTC) Date: Tue, 8 Jun 2021 14:29:01 +0200 From: Peter Rajnoha To: LVM general discussion and development Message-ID: <20210608122901.o7nw3v56kt756acu@alatyr-rpi.brq.redhat.com> References: <20210607214835.GB8181@redhat.com> MIME-Version: 1.0 In-Reply-To: <20210607214835.GB8181@redhat.com> User-Agent: NeoMutt/20180716 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-loop: linux-lvm@redhat.com Cc: "zkabelac@redhat.com" , Heming Zhao , Martin Wilck Subject: Re: [linux-lvm] Discussion: performance issue on event activation mode X-BeenThere: linux-lvm@redhat.com X-Mailman-Version: 2.1.12 Precedence: junk Reply-To: LVM general discussion and development List-Id: LVM general discussion and development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: linux-lvm-bounces@redhat.com Errors-To: linux-lvm-bounces@redhat.com X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=linux-lvm-bounces@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Disposition: inline Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit On Mon 07 Jun 2021 16:48, David Teigland wrote: > On Mon, Jun 07, 2021 at 03:48:30PM +0000, Martin Wilck wrote: > > On So, 2021-06-06 at 14:15 +0800, heming.zhao@suse.com wrote: > > > > > > 1. During boot phase, lvm2 automatically swithes to direct activation > > > mode > > > ("event_activation = 0"). After booted, switch back to the event > > > activation mode. > > > > > > Booting phase is a speical stage. *During boot*, we could "pretend" > > > that direct > > > activation (event_activation=0) is set, and rely on lvm2-activation- > > > *.service > > > for PV detection. Once lvm2-activation-net.service has finished, we > > > could > > > "switch on" event activation. > > > > I like this idea. Alternatively, we could discuss disabling event > > activation only in the "coldplug" phase after switching root (i.e. > > between start of systemd-udev-trigger.service and lvm2- > > activation.service), because that's the critical time span during which > > 1000s of events can happen simultaneously. > > If there are say 1000 PVs already present on the system, there could be > real savings in having one lvm command process all 1000, and then switch > over to processing uevents for any further devices afterward. The switch > over would be delicate because of the obvious races involved with new devs > appearing, but probably feasible. Maybe to avoid the race, we could possibly write the proposed "/run/lvm2/boot-finished" right before we initiate scanning in "vgchange -aay" that is a part of the lvm2-activation-net.service (the last service to do the direct activation). A few event-based pvscans could fire during the window between "scan initiated phase" in lvm2-activation-net.service's "ExecStart=vgchange -aay..." and the originally proposed "ExecStartPost=/bin/touch /run/lvm2/boot-finished", but I think still better than missing important uevents completely in this window. Peter _______________________________________________ linux-lvm mailing list linux-lvm@redhat.com https://listman.redhat.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/