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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B1B3BC433F5 for ; Thu, 30 Sep 2021 15:56:03 +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 3B57861411 for ; Thu, 30 Sep 2021 15:56:03 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 3B57861411 Authentication-Results: mail.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=redhat.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1633017362; 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=JnqB54jjhTVcAi4iDjbEiBaeGR03uFn7UYQrLCkUNGw=; b=YW4cxLBScs1HSHcinnS+utGJE/dY4ifuQN+Hl3lCmKzUr6DzsQok21Rwp1fd/ADe2RdArN gt3UCNpgCcWFn7Zn6nWjdk2WtVJY0btSGLx4Hx5dmHDdmRpkzRm+/pVGQzklmMg5M2GNXy dG0GKTf+A2oqEfeNg233aqdiX5RAFBU= 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-254-UYxDU-G_P868Qj5DAsaiHw-1; Thu, 30 Sep 2021 11:56:00 -0400 X-MC-Unique: UYxDU-G_P868Qj5DAsaiHw-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id C367B100CCC0; Thu, 30 Sep 2021 15:55:52 +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 C90EF60BE5; Thu, 30 Sep 2021 15:55:51 +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 A13F94EA2A; Thu, 30 Sep 2021 15:55:47 +0000 (UTC) Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) by lists01.pubmisc.prod.ext.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id 18UFtjeL015647 for ; Thu, 30 Sep 2021 11:55:45 -0400 Received: by smtp.corp.redhat.com (Postfix) id AB2F55C3DF; Thu, 30 Sep 2021 15:55:45 +0000 (UTC) Received: from redhat.com (unknown [10.15.80.136]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 1E4E05C1A1; Thu, 30 Sep 2021 15:55:45 +0000 (UTC) Date: Thu, 30 Sep 2021 10:55:42 -0500 From: David Teigland To: Peter Rajnoha Message-ID: <20210930155542.GB32174@redhat.com> References: <20210607214835.GB8181@redhat.com> <20210608122901.o7nw3v56kt756acu@alatyr-rpi.brq.redhat.com> <20210909194417.GC19437@redhat.com> <20210927100032.xczilyd5263b4ohk@alatyr-rpi.brq.redhat.com> <20210927153822.GA4779@redhat.com> <20210929213952.ws2qpmedaajs5wlx@alatyr-rpi.brq.redhat.com> MIME-Version: 1.0 In-Reply-To: <20210929213952.ws2qpmedaajs5wlx@alatyr-rpi.brq.redhat.com> User-Agent: Mutt/1.8.3 (2017-05-23) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-loop: linux-lvm@redhat.com Cc: zkabelac@redhat.com, bmarzins@redhat.com, martin.wilck@suse.com, heming.zhao@suse.com, linux-lvm@redhat.com 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 2.79 on 10.5.11.12 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 Wed, Sep 29, 2021 at 11:39:52PM +0200, Peter Rajnoha wrote: > Hmm, thinking about this, I've just realized one more important and related > thing here I didn't realize before - the LVM regex filters! These may contain > symlink names as one can find them in /dev. But for those symlinks, we need > to be sure that the rules are already applied. This practically means that: At least at RH we're enabling the devices file by default (meaning no filter) in the same timeframe that we're looking at these activation services. So, I don't think this is a big factor. > - For non-event-based activation, we need udev-settle (so we're sure > all the rules are applied for all devices we might be scanning). > > - For event-based activation, we need to be sure that we use "RUN" > rule, not any of "IMPORT{program}" or "PROGRAM" rule. The difference > is that the "RUN" rules are applied after all the other udev rules are > already applied for current uevent, including creation of symlinks. And > currently, we have IMPORT{program}="pvscan..." in our rule, > unfortunately... That's pretty subtle, I'm wary about propagating such specific and delicate behavior, seems fragile. > The nodes are already there, the symlinks could be missing because the > udev rules haven't been processed yet. > > Non-event-based LVM activation needs to wait for settle for sure (because > there's full scan across all devices). > > Event-based LVM activation just needs to be sure that: > > - the pvscan only scans the single device (the one for which there's > the uevent currently being processed), > > - the pvscan should be called in a way that we have all the symlinks > in place so the regex filter still works for symlinks (== putting > the pvscan onto a RUN exec queue). I think we're looking at a udev-settle dependency (or alternative) for all cases, best to just make that explicit and consistent, and isolated in one place. I'm not really seeing a downside to that. Then, focus efforts on refining a replacement. If the subtle dependencies are spread around then it's hard to extract and improve the unwanted parts. Dave _______________________________________________ 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/