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 7BA0BC433F5 for ; Tue, 21 Sep 2021 02:03:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 63D1061157 for ; Tue, 21 Sep 2021 02:03:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242662AbhIUCFL (ORCPT ); Mon, 20 Sep 2021 22:05:11 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:32934 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235914AbhIUBsS (ORCPT ); Mon, 20 Sep 2021 21:48:18 -0400 Received: from mail-oi1-x232.google.com (mail-oi1-x232.google.com [IPv6:2607:f8b0:4864:20::232]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D1153C04983C for ; Mon, 20 Sep 2021 14:30:22 -0700 (PDT) Received: by mail-oi1-x232.google.com with SMTP id u22so18478103oie.5 for ; Mon, 20 Sep 2021 14:30:22 -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=3qBGf2RxdhMVJ9ELb5q3Rnbf1pGunp9HuS2pZq9lZ+k=; b=Txim1HEdFX3kooa4u2VUlvVTbqhBKnGZXNnAOJ8Y7I7FTyK1jzLQHGNLTFXvMqDqcV qc4PvxrVl8ZztYq9D0K7ASe/bwxdeHMTBfu/Ee6YzByjJxT56OS10K7/7/UgQcm1gZYj dTJzOw4aJqwZkS69gxuHKg4XFXbsncrkiblYbt+ZsxgV3YGNxUuXd5JTjDyMqA4WcHuX KGtLcPS11r/oZmK/E+NPTiY7ihAykTBT0fJUEH3Dyj9mT7ZoPAl782E1g1gSMqfx857v wmXpsCa//X9KoLZQz3/NKsQPG3/bgc5aZKwm/kYugPl73rgU6jzMtFOsTu22m8dsC+zK KgdQ== 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=3qBGf2RxdhMVJ9ELb5q3Rnbf1pGunp9HuS2pZq9lZ+k=; b=ThcpbYjH+pUoi2Tn59tia6YSIavE6MwYUkqYdXzxGn5ShTZVcXSZeHpj/8Qk9XDZDl BoTvBJm0tK7QnKU3DSTWsleKBAbwygnT0zede4Vff2uutxRLdr/tW6zOXV5/CSJtjuRs 9l1BVpFh540Go8fPl6BWsA6tswsonNwRjoiIeda8iY/bYUvZ2mpAR5+2M+t9SoiWBAYT bd6NVuHRJczgj6JpBFkAIfrUFxSZGJGgAHScMtifXNRqx8cZ3nScJpnVWfCEUsFoIwvS mzi53G1giPK4rWSBL7O8Hr95d3bFKeyR1AjBf/oUmP2LeQLwGFHbJwRLSTO6C6FvW7Em xTNg== X-Gm-Message-State: AOAM531F4HsVV5j167MvOLYrsms+0O9uCNncfBRN0At0SL80Z2CeVfHR PQUDUGnvECnwN7jww7sw4PQdcp2oVXgCe13CjfcHeg== X-Google-Smtp-Source: ABdhPJwW0yn7WSbY2KJXuduv0Kh6DBTWYhyvEYlj8ObHH6kpg8wcsoq1FGaI1T/Y9KtI//Xio/ZA4DUBx52SeP+uHuo= X-Received: by 2002:a05:6808:6c2:: with SMTP id m2mr941032oih.63.1632173421950; Mon, 20 Sep 2021 14:30:21 -0700 (PDT) MIME-Version: 1.0 References: <20210917210640.214211-1-bgeffon@google.com> In-Reply-To: From: Brian Geffon Date: Mon, 20 Sep 2021 17:29:45 -0400 Message-ID: Subject: Re: [PATCH] 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-kernel@vger.kernel.org On Mon, Sep 20, 2021 at 5:15 PM Minchan Kim wrote: > > On Fri, Sep 17, 2021 at 02:06:40PM -0700, Brian Geffon wrote: > > This change introduces a new sysfs file for the zram idle interface. > > The current idle interface has only a single mode "all." This is > > severely limiting in that it requires that you have the foresight > > to know that you'll want to have pages idle at some point in the future > > and forces the user to mark everything as idle. > > > > This new proposed file idle_aged takes a single integer argument which > > represents the age of the pages (in seconds since access) to mark as idle. > > Because it requires accessed tracking it is only enabled when > > CONFIG_ZRAM_MEMORY_TRACKING is enabled. There are a few > > reasons why this is being proposed as a new file rather than extending > > the existing file. The first reason is that it wouldn't allow more code > > sharing as this change already refactors the existing code to do so. > > Secondly, having a standalone file allows a caller to quickly check if this > > idle_aged interface is supported. Finally, it simplifies the parsing > > logic because now you only need to parse an int rather than more complex > > logic which would need to parse things like "aged 50." > > I am not convinced with create new sysfs node to support the aged time. > The reason I used the "all" was to have the room to support the aged > time as you suggested for the future. IOW, If the value is not "all" but > "only numeric", we could take it as "aged" value. > > And then, we can write up in the doc "The age-based idle" supported by > kernel version 5.XX with CONFIG_ZRAM_MEMORY_TRACKING. > I understand the separate interface will make code simple but not sure > it's worth to create another sysfs knob. > > Any thoughts? Sure, Sergey had similar feedback on that. I'll mail a new patch that uses the existing knob but attempts to parse the input as an integer. > > > > > Signed-off-by: Brian Geffon > > --- > > Documentation/admin-guide/blockdev/zram.rst | 11 ++- > > drivers/block/zram/zram_drv.c | 75 +++++++++++++++++---- > > 2 files changed, 70 insertions(+), 16 deletions(-) > > > > diff --git a/Documentation/admin-guide/blockdev/zram.rst b/Documentation/admin-guide/blockdev/zram.rst > > index 700329d25f57..ecd1c4916a1c 100644 > > --- a/Documentation/admin-guide/blockdev/zram.rst > > +++ b/Documentation/admin-guide/blockdev/zram.rst > > @@ -209,6 +209,8 @@ compact WO trigger memory compaction > > debug_stat RO this file is used for zram debugging purposes > > backing_dev RW set up backend storage for zram to write out > > idle WO mark allocated slot as idle > > +idle_aged WO mark allocated slot older than 'age' seconds > > + as idle (see later) > > ====================== ====== =============================================== > > > > > > @@ -325,8 +327,13 @@ as idle:: > > > > echo all > /sys/block/zramX/idle > > > > -From now on, any pages on zram are idle pages. The idle mark > > -will be removed until someone requests access of the block. > > +Alternatively if the config option CONFIG_ZRAM_MEMORY_TRACKING is enabled > > +the idle_aged interface can be used to mark only pages older than 'age' > > +seconds as idle:: > > + > > + echo 86400 > /sys/block/zramX/idle_aged > > + > > +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. > > > > 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..a371dc0edf9d 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. > > @@ -314,16 +308,63 @@ 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 || cutoff >= zram->table[index].ac_time); > > I am not sure it's a good idea to compare those ktime_t directly > without using the ktime API(e.g., ktime_after or ktime_before). > Maybe, we can get age_sec ktime_t directly as a argument and then > use the ktime API with ktime_get_boottime to compare them. I will make this change in the next version of the patch. > > > +#endif > > + if (is_idle) > > + zram_set_flag(zram, index, ZRAM_IDLE); > > + } > > zram_slot_unlock(zram, index); > > } > > +} > > + > > +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); > > + > > + if (!sysfs_streq(buf, "all")) > > + return -EINVAL; > > + > > + down_read(&zram->init_lock); > > + if (!init_done(zram)) { > > + up_read(&zram->init_lock); > > + return -EINVAL; > > + } > > > > + /* Mark everything as idle */ > > + mark_idle(zram, 0); > > up_read(&zram->init_lock); > > > > return len; > > } > > > > +#ifdef CONFIG_ZRAM_MEMORY_TRACKING > > +static ssize_t idle_aged_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; > > + u64 age_sec; > > + ssize_t rv = -EINVAL; > > + > > + down_read(&zram->init_lock); > > + if (!init_done(zram)) > > + goto out; > > + > > + if (kstrtoull(buf, 10, &age_sec)) > > + goto out; > > + > > + rv = len; > > + cutoff_time = ktime_sub(ktime_get_boottime(), ns_to_ktime(age_sec * NSEC_PER_SEC)); > > + mark_idle(zram, cutoff_time); > > +out: > > + up_read(&zram->init_lock); > > + return rv; > > +} > > +#endif > > + > > #ifdef CONFIG_ZRAM_WRITEBACK > > static ssize_t writeback_limit_enable_store(struct device *dev, > > struct device_attribute *attr, const char *buf, size_t len) > > @@ -1840,6 +1881,9 @@ static DEVICE_ATTR_WO(reset); > > static DEVICE_ATTR_WO(mem_limit); > > static DEVICE_ATTR_WO(mem_used_max); > > static DEVICE_ATTR_WO(idle); > > +#ifdef CONFIG_ZRAM_MEMORY_TRACKING > > +static DEVICE_ATTR_WO(idle_aged); > > +#endif > > static DEVICE_ATTR_RW(max_comp_streams); > > static DEVICE_ATTR_RW(comp_algorithm); > > #ifdef CONFIG_ZRAM_WRITEBACK > > @@ -1857,6 +1901,9 @@ static struct attribute *zram_disk_attrs[] = { > > &dev_attr_mem_limit.attr, > > &dev_attr_mem_used_max.attr, > > &dev_attr_idle.attr, > > +#ifdef CONFIG_ZRAM_MEMORY_TRACKING > > + &dev_attr_idle_aged.attr, > > +#endif > > &dev_attr_max_comp_streams.attr, > > &dev_attr_comp_algorithm.attr, > > #ifdef CONFIG_ZRAM_WRITEBACK > > -- > > 2.33.0.464.g1972c5931b-goog > > Thank you for looking, Brian