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=-23.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_IN_DEF_DKIM_WL autolearn=unavailable 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 82519C433F5 for ; Thu, 23 Sep 2021 00:43:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5495961019 for ; Thu, 23 Sep 2021 00:43:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238631AbhIWAow (ORCPT ); Wed, 22 Sep 2021 20:44:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57992 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238687AbhIWAov (ORCPT ); Wed, 22 Sep 2021 20:44:51 -0400 Received: from mail-oi1-x234.google.com (mail-oi1-x234.google.com [IPv6:2607:f8b0:4864:20::234]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3FFC5C061757 for ; Wed, 22 Sep 2021 17:43:21 -0700 (PDT) Received: by mail-oi1-x234.google.com with SMTP id s69so7169347oie.13 for ; Wed, 22 Sep 2021 17:43:21 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=/YzPGdIXUc/n+UBh3Q3cyORP7gAvTv0HxiAeEJD2X/M=; b=o9cAfzvPlxeahlg+EGKgy1FyV3/N+o2QmQ1HklIF0pZG+dic83eqjqpr1UCsFGjUZY g2heg7E3OCpWc/asmqQY5rFyZ+ysANmmp0qK+qHKeXBojcc/pLy4pa51DlWNv/vPYpem 7vnxm2RaEpXfZpdIyYC91I7XXpUY2APoDdzLWnIhgeLnNfoatSJvRCwvq/t1VT00KkHk 9bOnggMze/BZaZ8oPUf69pu2nIgREXa3ZXmAHqQsGBZjmoBUi5c2CmK0LjLflvv/gDRF fSg+yMyHXwOcnHjvvp0EbRlr3lMHsw2lQQVYlB5ERGMSVXFTVQ/bqHM8JeJHdYm/W/Hr RdkA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=/YzPGdIXUc/n+UBh3Q3cyORP7gAvTv0HxiAeEJD2X/M=; b=qqNVm48aQEJQ7DjQTxyZiWIGzEhk/i3v8mDtAIbddmFhhl66af1ks/wVHILHlQzDeF 6zfOGztbQkxEcl7sy6DkaAqB13AaDg/REh/2K4+isucxeyOCLXLOGYxB7R1FWr8W+K5s Ucqwr9nID1gWuOAt2OyukDIIgMVT+AyyDN6xjUM0nupLkzOZq80h6fXpKCm1DEY7+jAE t3iuRvgdh4A/kv8XW7SDj18Lgl/eFP0b6vAXnQQQhVp3xlB/oKVvtntsCFcUho93dTZC LweADmYmqHSYq5JbaRleSWFivlW5cKzbTgsZOmXYch93rN6iwTmBX9k1nQtyd5uEBiYh QdsQ== X-Gm-Message-State: AOAM532klVxkUTVQQXZSw/njC8sA27sOAbrQcE7Aydwg19zYsx68i6Z7 piLdN3SA98j8Ll94hyUf34NNM7CCgE3t9XYJWXBvlQ== X-Google-Smtp-Source: ABdhPJxOK+CVcYZjH4ildch2fjdVvtzb7hwaN4QxvcaP1yaHV+0zUJ+RxGnAcxkjCSbUISAVEIo7hPbbn2VKH3Xhx4E= X-Received: by 2002:aca:af56:: with SMTP id y83mr1656895oie.170.1632357800207; Wed, 22 Sep 2021 17:43:20 -0700 (PDT) MIME-Version: 1.0 References: <20210917210640.214211-1-bgeffon@google.com> <20210921194336.947226-1-bgeffon@google.com> In-Reply-To: From: Brian Geffon Date: Wed, 22 Sep 2021 20:42:44 -0400 Message-ID: Subject: Re: [PATCH v3] zram: Introduce an aged idle interface To: Minchan Kim Cc: Andrew Morton , Nitin Gupta , Sergey Senozhatsky , Jonathan Corbet , LKML , linux-doc@vger.kernel.org, linux-block@vger.kernel.org, Suleiman Souhlal , Jesse Barnes Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org Hi Minchan, Thank you for taking a look. I'm happy to make that change, but I personally cannot see why userspace would want to do something like idle pages older than "0x3C seconds" or "0o250600 seconds," it just seems like a strange way to represent seconds. What do you think? Brian On Wed, Sep 22, 2021 at 8:09 PM Minchan Kim wrote: > > On Tue, Sep 21, 2021 at 12:43:36PM -0700, Brian Geffon wrote: > > This change introduces an aged idle interface to the existing > > idle sysfs file for zram. > > > > When CONFIG_ZRAM_MEMORY_TRACKING is enabled the idle file > > now also accepts an integer argument. This integer is the > > age (in seconds) of pages to mark as idle. The idle file > > still supports 'all' as it always has. This new approach > > allows for much more control over which pages get marked > > as idle. > > > > v2 -> v3: > > - Correct unused variable warning when > > CONFIG_ZRAM_MEMORY_TRACKING is not enabled. > > v1 -> v2: > > - Switch to using existing idle file. > > - Dont compare ktime directly. > > > > Signed-off-by: Brian Geffon > > --- > > Documentation/admin-guide/blockdev/zram.rst | 8 +++ > > drivers/block/zram/zram_drv.c | 60 +++++++++++++++------ > > 2 files changed, 52 insertions(+), 16 deletions(-) > > > > diff --git a/Documentation/admin-guide/blockdev/zram.rst b/Documentation/admin-guide/blockdev/zram.rst > > index 700329d25f57..8c8a92e5c00c 100644 > > --- a/Documentation/admin-guide/blockdev/zram.rst > > +++ b/Documentation/admin-guide/blockdev/zram.rst > > @@ -328,6 +328,14 @@ as idle:: > > From now on, any pages on zram are idle pages. The idle mark > > will be removed until someone requests access of the block. > > IOW, unless there is access request, those pages are still idle pages. > > +Additionally, when CONFIG_ZRAM_MEMORY_TRACKING is enabled pages can be > > +marked as idle based on how long (in seconds) it's been since they were > > +last accessed, in seconds:: > > + > > + echo 86400 > /sys/block/zramX/idle > > + > > +In this example all pages which haven't been accessed in more than 86400 > > +seconds (one day) will be marked idle. > > > > Admin can request writeback of those idle pages at right timing via:: > > > > diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c > > index fcaf2750f68f..2af5cdb8da1a 100644 > > --- a/drivers/block/zram/zram_drv.c > > +++ b/drivers/block/zram/zram_drv.c > > @@ -291,22 +291,16 @@ static ssize_t mem_used_max_store(struct device *dev, > > return len; > > } > > > > -static ssize_t idle_store(struct device *dev, > > - struct device_attribute *attr, const char *buf, size_t len) > > +/* > > + * Mark all pages which are older than or equal to cutoff as IDLE. > > + * Callers should hold the zram init lock in read mode > > + **/ > > +static void mark_idle(struct zram *zram, ktime_t cutoff) > > { > > - struct zram *zram = dev_to_zram(dev); > > + int is_idle = 1; > > unsigned long nr_pages = zram->disksize >> PAGE_SHIFT; > > int index; > > > > - if (!sysfs_streq(buf, "all")) > > - return -EINVAL; > > - > > - down_read(&zram->init_lock); > > - if (!init_done(zram)) { > > - up_read(&zram->init_lock); > > - return -EINVAL; > > - } > > - > > for (index = 0; index < nr_pages; index++) { > > /* > > * Do not mark ZRAM_UNDER_WB slot as ZRAM_IDLE to close race. > > @@ -314,14 +308,48 @@ static ssize_t idle_store(struct device *dev, > > */ > > zram_slot_lock(zram, index); > > if (zram_allocated(zram, index) && > > - !zram_test_flag(zram, index, ZRAM_UNDER_WB)) > > - zram_set_flag(zram, index, ZRAM_IDLE); > > + !zram_test_flag(zram, index, ZRAM_UNDER_WB)) { > > +#ifdef CONFIG_ZRAM_MEMORY_TRACKING > > + is_idle = (!cutoff || ktime_after(cutoff, zram->table[index].ac_time)); > > +#endif > > + if (is_idle) > > + zram_set_flag(zram, index, ZRAM_IDLE); > > + } > > zram_slot_unlock(zram, index); > > } > > +} > > > > - up_read(&zram->init_lock); > > +static ssize_t idle_store(struct device *dev, > > + struct device_attribute *attr, const char *buf, size_t len) > > +{ > > + struct zram *zram = dev_to_zram(dev); > > + ktime_t cutoff_time = 0; > > + ssize_t rv = -EINVAL; > > > > - return len; > > + if (!sysfs_streq(buf, "all")) { > > +#ifdef CONFIG_ZRAM_MEMORY_TRACKING > > + u64 age_sec; > > + /* If it did not parse as 'all' try to treat it as an integer */ > > + if (!kstrtoull(buf, 10, &age_sec)) > > nit: > Do we need such limit base which work with only 10 base? > Passing 0 would give more flexibility. > > Otherwise, looks good to me. > > Thanks, Brian. > > > + cutoff_time = ktime_sub(ktime_get_boottime(), > > + ns_to_ktime(age_sec * NSEC_PER_SEC)); > > + else > > +#endif > > + goto out; > > + } > > + > > + down_read(&zram->init_lock); > > + if (!init_done(zram)) > > + goto out_unlock; > > + > > + /* A age_sec of 0 marks everything as idle, this is the "all" behavior */ > > + mark_idle(zram, cutoff_time); > > + rv = len; > > + > > +out_unlock: > > + up_read(&zram->init_lock); > > +out: > > + return rv; > > } > > > > #ifdef CONFIG_ZRAM_WRITEBACK > > -- > > 2.33.0.464.g1972c5931b-goog > >