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=-7.5 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,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 00C9FC47094 for ; Mon, 7 Jun 2021 21:30:44 +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 97911611BD for ; Mon, 7 Jun 2021 21:30:43 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 97911611BD 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=1623101442; 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=2DOP5fvHti8dNZXr9YH3P9DFwE091kJzWU+ChQ+jXM0=; b=THYH8D0eBnmpotsnqdG5+KYbevpHyI6sf82VQxmy7/ZxI7Aa9itrLGzPEbyKIFZOteekYw PgPn1yRr59zNW6lP7f+DJf7E8HwdgZS364EuFzHppBRcU6AXQUrMATKFEgCUp10H83nkne 6PuHdf8Lu6wCDbEXRpWPPYTPdyve2mo= 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-378-rUqdKNUoPT6CFqR1F0qZBg-1; Mon, 07 Jun 2021 17:30:40 -0400 X-MC-Unique: rUqdKNUoPT6CFqR1F0qZBg-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 2168618BA281; Mon, 7 Jun 2021 21:30:35 +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 229AB5D6D3; Mon, 7 Jun 2021 21:30:33 +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 851E444A59; Mon, 7 Jun 2021 21:30:20 +0000 (UTC) Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) by lists01.pubmisc.prod.ext.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id 157LUHLt015564 for ; Mon, 7 Jun 2021 17:30:17 -0400 Received: by smtp.corp.redhat.com (Postfix) id 30FD65B826; Mon, 7 Jun 2021 21:30:17 +0000 (UTC) Received: from redhat.com (null.msp.redhat.com [10.15.80.136]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 46EED1349A; Mon, 7 Jun 2021 21:30:05 +0000 (UTC) Date: Mon, 7 Jun 2021 16:30:03 -0500 From: David Teigland To: Martin Wilck Message-ID: <20210607213003.GA8181@redhat.com> References: MIME-Version: 1.0 In-Reply-To: User-Agent: Mutt/1.8.3 (2017-05-23) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-loop: linux-lvm@redhat.com Cc: "zkabelac@redhat.com" , "rogerheflin@gmail.com" , "linux-lvm@redhat.com" , Heming Zhao 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 10.5.11.15 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="iso-8859-1" Content-Transfer-Encoding: quoted-printable On Mon, Jun 07, 2021 at 10:27:20AM +0000, Martin Wilck wrote: > Most importantly, this was about LVM2 scanning of physical volumes. The > number of udev workers has very little influence on=A0PV scanning, > because the udev rules only activate systemd service. The actual > scanning takes place in lvm2-pvscan@.service. And unlike udev, there's > no limit for the number of instances of a given systemd service > template that can run at any given time. Excessive device scanning has been the historical problem in this area, but Heming mentioned dev_cache_scan() specifically as a problem. That was surprising to me since it doesn't scan/read devices, it just creates a list of device names on the system (either readdir in /dev or udev listing.) If there are still problems with excessive scannning/reading, we'll need some more diagnosis of what's happening, there could be some cases we've missed. 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/