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=-9.6 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS autolearn=ham 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 7ED7EC2D0A3 for ; Wed, 4 Nov 2020 15:29:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2A22A2074B for ; Wed, 4 Nov 2020 15:29:17 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="E8GlDDUp" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730279AbgKDP3Q (ORCPT ); Wed, 4 Nov 2020 10:29:16 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55090 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730196AbgKDP3P (ORCPT ); Wed, 4 Nov 2020 10:29:15 -0500 Received: from mail-oo1-xc41.google.com (mail-oo1-xc41.google.com [IPv6:2607:f8b0:4864:20::c41]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D2B5AC0613D3 for ; Wed, 4 Nov 2020 07:29:14 -0800 (PST) Received: by mail-oo1-xc41.google.com with SMTP id l4so601815oos.7 for ; Wed, 04 Nov 2020 07:29:14 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=KMJnWqVtiUqJyCWV1g8Xa59THK5Gud7UZMLHyBYsRO8=; b=E8GlDDUpTa2xu4DAlUG+8mHM+Zdu+N9oWUMzNN4z2kQIc0kJh28nfKsohswQg3kAyU rKxFRwJPR6hQrl5a0x/tAljNAo9asFwpnDJqQmqrkuusd62hEGNPjeSsHVaKAw5jLrzL 2CvYNfGtDAlpN08blm80Hzbhrhm2ncT0ZCUY+jveRFiMlqcaj6YgyRKZbPwCbS+UVcH0 5DYORLuZXlLR4UWAHrzhb+2qdD8/9WGxH6HGTiEU5M5HetfBsbKWa7cPYUOB4dVSx4x7 Xm+954FQ85elgWDmuXiLbBYqLW9cWP+gOTVK/cSKhtF2QJ2pgAV1Vny+AdF6WHUbM5Z+ PQTQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=KMJnWqVtiUqJyCWV1g8Xa59THK5Gud7UZMLHyBYsRO8=; b=T1Z9dRLvMo8PMZOIC5vtwG1tt4D+L2VneQZTIByWd1nr8hu6CVhHBwufYznjFWyMvl sc469qGgzTIN9pXqrm50HHnmwVPXRtXV8j9JFBHWS+Kt56vDbQLKQoWa2v9rbPH5sP8w fha1X0MWrylcQ5+MSO+KGE6Xt0kNSCeQoMu0P9fGCSBcVKxr5oA3KxP071I/lZwHfowB yVYeymlRQB74xNPZtd0tvndyNthXobIdR6t3FcyJ3ZdoQuThc/BfDiIGzJ9/MhRnchrj SDSX8ZnB00sz8TxvyfteJfCSxEUb6lNPVUejhxvs1Gub8oCi389k0AO45mk/FGiAvkQM Z71w== X-Gm-Message-State: AOAM533wWweFZtdf7Iud1/0d7dMQz/rIe04gSX/6ueHZVnqGqzAYc8pm 6bq/Rr1bQKuRSNFeP3MmbNft4dwlkpZDj1SESWc= X-Google-Smtp-Source: ABdhPJwkFxgQrr9244Ca9+onYd2xF7krojzy1ZOFF+ucI/EU8j848Z3meekwsNIsg/4sJfvhrdSDTiIyj/MAF6kYS14= X-Received: by 2002:a4a:9cc3:: with SMTP id d3mr19072528ook.4.1604503754239; Wed, 04 Nov 2020 07:29:14 -0800 (PST) MIME-Version: 1.0 References: <2a3d84dfc9384eed8659963d1dafedabb3f17c75.1604444952.git.asml.silence@gmail.com> In-Reply-To: <2a3d84dfc9384eed8659963d1dafedabb3f17c75.1604444952.git.asml.silence@gmail.com> From: Amy Parker Date: Wed, 4 Nov 2020 07:29:03 -0800 Message-ID: Subject: Re: [PATCH 1/4] btrfs: discard: speed up discard up to iops_limit To: Pavel Begunkov Cc: Chris Mason , Josef Bacik , David Sterba , Btrfs BTRFS Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On Wed, Nov 4, 2020 at 1:50 AM Pavel Begunkov wrote: > > Instead of using iops_limit only for cutting off extremes, calculate the > discard delay directly from it, so it closely follows iops_limit and > doesn't under-discarding even though quotas are not saturated. This sounds like it potentially be a great performance boost, do you have any performance metrics regarding this patch? > > Signed-off-by: Pavel Begunkov > --- > fs/btrfs/discard.c | 10 +++++----- > 1 file changed, 5 insertions(+), 5 deletions(-) > > diff --git a/fs/btrfs/discard.c b/fs/btrfs/discard.c > index 741c7e19c32f..76796a90e88d 100644 > --- a/fs/btrfs/discard.c > +++ b/fs/btrfs/discard.c > @@ -519,7 +519,6 @@ void btrfs_discard_calc_delay(struct btrfs_discard_ctl *discard_ctl) > s64 discardable_bytes; > u32 iops_limit; > unsigned long delay; > - unsigned long lower_limit = BTRFS_DISCARD_MIN_DELAY_MSEC; > > discardable_extents = atomic_read(&discard_ctl->discardable_extents); > if (!discardable_extents) > @@ -550,11 +549,12 @@ void btrfs_discard_calc_delay(struct btrfs_discard_ctl *discard_ctl) > > iops_limit = READ_ONCE(discard_ctl->iops_limit); > if (iops_limit) > - lower_limit = max_t(unsigned long, lower_limit, > - MSEC_PER_SEC / iops_limit); > + delay = MSEC_PER_SEC / iops_limit; > + else > + delay = BTRFS_DISCARD_TARGET_MSEC / discardable_extents; Looks good to me. I wonder why there wasn't handling of if iops_limit was unfindable before? > > - delay = BTRFS_DISCARD_TARGET_MSEC / discardable_extents; > - delay = clamp(delay, lower_limit, BTRFS_DISCARD_MAX_DELAY_MSEC); > + delay = clamp(delay, BTRFS_DISCARD_MIN_DELAY_MSEC, > + BTRFS_DISCARD_MAX_DELAY_MSEC); > discard_ctl->delay = msecs_to_jiffies(delay); > > spin_unlock(&discard_ctl->lock); > -- > 2.24.0 > This patch looks all great to me. Best regards, Amy Parker (they/them)