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=-15.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 9D287C4743D for ; Tue, 8 Jun 2021 09:28:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 76D696128B for ; Tue, 8 Jun 2021 09:28:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230190AbhFHJ35 (ORCPT ); Tue, 8 Jun 2021 05:29:57 -0400 Received: from mail.kernel.org ([198.145.29.99]:37756 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229507AbhFHJ34 (ORCPT ); Tue, 8 Jun 2021 05:29:56 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 72D166124C; Tue, 8 Jun 2021 09:28:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1623144484; bh=u/yn7qdyg2jplF/gHxRTO0ZByTH2g4Z41ES/bS2ZEpE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=vtlPXWHw03L/hDmiA5HUErLr5DckpuwpDtSY6cbWuMI9ey8p5BwoEf8QH0IFQ71FC +BG2oHucIybGH7+JBhwG/k4l3j3bhUNsuh4yWD3cOEy//fBTyCi3JStstMsH8TRA0n s2owd6UyymeLJCI3V1vEuD+gzCFu1R7uFRbjOTpo= Date: Tue, 8 Jun 2021 11:28:01 +0200 From: Greg KH To: yongw.pur@gmail.com Cc: minchan@kernel.org, ngupta@vflare.org, senozhatsky@chromium.org, axboe@kernel.dk, akpm@linux-foundation.org, songmuchun@bytedance.com, david@redhat.com, linux-kernel@vger.kernel.org, linux-block@vger.kernel.org, linux-mm@kvack.org, willy@infradead.org, linux-api@vger.kernel.org, lu.zhongjun@zte.com.cn, yang.yang29@zte.com.cn, zhang.wenya1@zte.com.cn, wang.yong12@zte.com.cn Subject: Re: [RFC PATCH V3] zram:calculate available memory when zram is used Message-ID: References: <1623080354-21453-1-git-send-email-yongw.pur@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1623080354-21453-1-git-send-email-yongw.pur@gmail.com> Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Mon, Jun 07, 2021 at 08:39:14AM -0700, yongw.pur@gmail.com wrote: > From: wangyong > > When zram is used, available+Swap free memory is obviously bigger than we > actually can use, because zram can compress memory by compression > algorithm and zram compressed data will occupy memory too. > > So, we can count the compression ratio of zram in the kernel. The space > will be saved by zram and other swap device are calculated as follows: > zram[swapfree - swapfree * compress ratio] + swapdev[swapfree] > We can evaluate the available memory of the whole system as: > MemAvailable+zram[swapfree - swapfree * compress ratio]+swapdev[swapfree] > > Add an entry to the /proc/meminfo file, returns swap will save space. > Which name is more appropriate is still under consideration. > There are several alternative names: SwapAvailable, SwapSaved, > SwapCompressible, Which is better? > > Adding new entries has little effect on user program, since parsers > usually parse by keywords > > Changes from v2: > *Add interface description document > *Other mistakes and problems fix > > Changes from v1: > *Use a new interface to return memory savings when using swap devices > *Zram add min_compr_ratio attr These "Changes" need to go below the --- line please. > > Signed-off-by: wangyong > --- > Documentation/admin-guide/blockdev/zram.rst | 6 ++ > Documentation/filesystems/proc.rst | 4 ++ > drivers/block/zram/zcomp.h | 8 +++ > drivers/block/zram/zram_drv.c | 19 ++++++ > drivers/block/zram/zram_drv.h | 1 + > fs/proc/meminfo.c | 1 + > include/linux/swap.h | 11 ++++ > mm/swapfile.c | 95 +++++++++++++++++++++++++++++ > mm/vmscan.c | 1 + > 9 files changed, 146 insertions(+) > > diff --git a/Documentation/admin-guide/blockdev/zram.rst b/Documentation/admin-guide/blockdev/zram.rst > index 700329d..3b7c4c4 100644 > --- a/Documentation/admin-guide/blockdev/zram.rst > +++ b/Documentation/admin-guide/blockdev/zram.rst > @@ -283,6 +283,12 @@ a single line of text and contains the following stats separated by whitespace: > Unit: 4K bytes > ============== ============================================================= > > +File /sys/block/zram/min_compr_ratio > + > +The min_compr_ratio file represents the min_compr_ratio during zram swapping out.The calculation formula is as follows: > +(orig_size * 100) / compr_data_size > + > + sysfs files need to be documented in Documentation/ABI/ files. You can reference them in other documentation files, but they need to be in the ABI/ directory as well. Also please wrap your lines at the proper length and use a ' ' after a '.' > 9) Deactivate > ============= > > diff --git a/Documentation/filesystems/proc.rst b/Documentation/filesystems/proc.rst > index 042c418..15d35ae 100644 > --- a/Documentation/filesystems/proc.rst > +++ b/Documentation/filesystems/proc.rst > @@ -961,6 +961,7 @@ You may not have all of these fields. > LowFree: 4432 kB > SwapTotal: 0 kB > SwapFree: 0 kB > + SwapAvailable: 0 kB > Dirty: 968 kB > Writeback: 0 kB > AnonPages: 861800 kB > @@ -1032,6 +1033,9 @@ SwapTotal > SwapFree > Memory which has been evicted from RAM, and is temporarily > on the disk > +SwapAvailable > + The memory savings when use swap devices. it takes zram > + compression ratio into considerations, when zram is used Trailing whitespace? Did you run your patch through scripts/checkpatch.pl first before sending it out? > Dirty > Memory which is waiting to get written back to the disk > Writeback > diff --git a/drivers/block/zram/zcomp.h b/drivers/block/zram/zcomp.h > index 40f6420..9c9cb96 100644 > --- a/drivers/block/zram/zcomp.h > +++ b/drivers/block/zram/zcomp.h > @@ -40,4 +40,12 @@ int zcomp_decompress(struct zcomp_strm *zstrm, > const void *src, unsigned int src_len, void *dst); > > bool zcomp_set_max_streams(struct zcomp *comp, int num_strm); > +#ifdef CONFIG_ZRAM > +int get_zram_major(void); > +#else > +int get_zram_major(void) > +{ > + return -1; > +} > +#endif > #endif /* _ZCOMP_H_ */ > diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c > index fcaf275..8f527e0 100644 > --- a/drivers/block/zram/zram_drv.c > +++ b/drivers/block/zram/zram_drv.c > @@ -59,6 +59,10 @@ static void zram_free_page(struct zram *zram, size_t index); > static int zram_bvec_read(struct zram *zram, struct bio_vec *bvec, > u32 index, int offset, struct bio *bio); > > +int get_zram_major(void) > +{ > + return zram_major; Why does anyone need the zram major number? > +} > > static int zram_slot_trylock(struct zram *zram, u32 index) > { > @@ -1040,6 +1044,19 @@ static ssize_t compact_store(struct device *dev, > return len; > } > > +static ssize_t min_compr_ratio_show(struct device *dev, > + struct device_attribute *attr, char *buf) > +{ > + struct zram *zram = dev_to_zram(dev); > + ssize_t ret; > + > + down_read(&zram->init_lock); > + ret = scnprintf(buf, PAGE_SIZE, "%d\n", atomic_read(&zram->stats.min_compr_ratio)); > + up_read(&zram->init_lock); You are using an atomic variable _AND_ a read lock? Are you sure that makes sense? And please use sysfs_emit() for sysfs files. > + > + return ret; > +} > + > static ssize_t io_stat_show(struct device *dev, > struct device_attribute *attr, char *buf) > { > @@ -1132,6 +1149,7 @@ static ssize_t debug_stat_show(struct device *dev, > return ret; > } > > +static DEVICE_ATTR_RO(min_compr_ratio); > static DEVICE_ATTR_RO(io_stat); > static DEVICE_ATTR_RO(mm_stat); > #ifdef CONFIG_ZRAM_WRITEBACK > @@ -1859,6 +1877,7 @@ static struct attribute *zram_disk_attrs[] = { > &dev_attr_idle.attr, > &dev_attr_max_comp_streams.attr, > &dev_attr_comp_algorithm.attr, > + &dev_attr_min_compr_ratio.attr, > #ifdef CONFIG_ZRAM_WRITEBACK > &dev_attr_backing_dev.attr, > &dev_attr_writeback.attr, > diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h > index 80c3b43..5717e06 100644 > --- a/drivers/block/zram/zram_drv.h > +++ b/drivers/block/zram/zram_drv.h > @@ -88,6 +88,7 @@ struct zram_stats { > atomic64_t bd_reads; /* no. of reads from backing device */ > atomic64_t bd_writes; /* no. of writes from backing device */ > #endif > + atomic_t min_compr_ratio; > }; > > struct zram { > diff --git a/fs/proc/meminfo.c b/fs/proc/meminfo.c > index 6fa761c..34a174b 100644 > --- a/fs/proc/meminfo.c > +++ b/fs/proc/meminfo.c > @@ -86,6 +86,7 @@ static int meminfo_proc_show(struct seq_file *m, void *v) > > show_val_kb(m, "SwapTotal: ", i.totalswap); > show_val_kb(m, "SwapFree: ", i.freeswap); > + show_val_kb(m, "SwapAvailable: ", count_avail_swaps()); > show_val_kb(m, "Dirty: ", > global_node_page_state(NR_FILE_DIRTY)); > show_val_kb(m, "Writeback: ", > diff --git a/include/linux/swap.h b/include/linux/swap.h > index bb48893..deed141 100644 > --- a/include/linux/swap.h > +++ b/include/linux/swap.h > @@ -515,6 +515,8 @@ extern int init_swap_address_space(unsigned int type, unsigned long nr_pages); > extern void exit_swap_address_space(unsigned int type); > extern struct swap_info_struct *get_swap_device(swp_entry_t entry); > sector_t swap_page_sector(struct page *page); > +extern void update_zram_zstats(void); > +extern u64 count_avail_swaps(void); > > static inline void put_swap_device(struct swap_info_struct *si) > { > @@ -689,6 +691,15 @@ static inline swp_entry_t get_swap_page(struct page *page) > return entry; > } > > +void update_zram_zstats(void) > +{ > +} > + > +u64 count_avail_swaps(void) > +{ > + return 0; > +} > + > #endif /* CONFIG_SWAP */ > > #ifdef CONFIG_THP_SWAP > diff --git a/mm/swapfile.c b/mm/swapfile.c > index 1e07d1c..5ce5100 100644 > --- a/mm/swapfile.c > +++ b/mm/swapfile.c > @@ -44,6 +44,7 @@ > #include > #include > #include > +#include "../drivers/block/zram/zram_drv.h" That's a big hint that this is not correct, please do not do this :( The core kernel should not depend on a random block driver's code. thanks, greg k-h