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=-0.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 2B7ABC43331 for ; Wed, 1 Apr 2020 16:07:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EEA922071A for ; Wed, 1 Apr 2020 16:07:00 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="NeorHoCi" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727541AbgDAQHA (ORCPT ); Wed, 1 Apr 2020 12:07:00 -0400 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:49901 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726974AbgDAQHA (ORCPT ); Wed, 1 Apr 2020 12:07:00 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1585757219; 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=uMimPNQSz3DwzlUI4yRmFriwIbIMmfcBK8Z2dXU9i+E=; b=NeorHoCi0hTx+BL51Bo7xUaVezMKQotl0yE825f+45C5knocoRbmJHFzwbs1AC+9Vzs5Xa lYFijzTgogn2Ode6tV1jyfWrQs5FffVYgo68Vz+JOJ6nJLr52QapdgANeEtEizAPJyZGRE tI2pLxXUynzOEWuyJY0GRlfEvwm0THk= 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-47--V5-xBXdNWu9JR4zNxt2LQ-1; Wed, 01 Apr 2020 12:06:57 -0400 X-MC-Unique: -V5-xBXdNWu9JR4zNxt2LQ-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id AFBC6801E6D; Wed, 1 Apr 2020 16:06:55 +0000 (UTC) Received: from warthog.procyon.org.uk (ovpn-114-243.ams2.redhat.com [10.36.114.243]) by smtp.corp.redhat.com (Postfix) with ESMTP id 61C0A5C3F8; Wed, 1 Apr 2020 16:06:52 +0000 (UTC) Organization: Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: References: <20200330211700.g7evnuvvjenq3fzm@wittgenstein> <1445647.1585576702@warthog.procyon.org.uk> <2418286.1585691572@warthog.procyon.org.uk> <20200401144109.GA29945@gardel-login> To: Miklos Szeredi Cc: dhowells@redhat.com, Lennart Poettering , Christian Brauner , Linus Torvalds , Al Viro , dray@redhat.com, Karel Zak , Miklos Szeredi , Steven Whitehouse , Jeff Layton , Ian Kent , andres@anarazel.de, keyrings@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Aleksa Sarai Subject: Re: Upcoming: Notifications, FS notifications and fsinfo() MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <2590639.1585757211.1@warthog.procyon.org.uk> Date: Wed, 01 Apr 2020 17:06:51 +0100 Message-ID: <2590640.1585757211@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Miklos Szeredi wrote: > I've still not heard a convincing argument in favor of a syscall. >From your own results, scanning 10000 mounts through mountfs and reading just two values from each is an order of magnitude slower without the effect of the dentry/inode caches. It gets faster on the second run because the mountfs dentries and inodes are cached - but at a cost of >205MiB of RAM. And it's *still* slower than fsinfo(). David