From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f49.google.com (mail-pa0-f49.google.com [209.85.220.49]) by kanga.kvack.org (Postfix) with ESMTP id 983B4280244 for ; Sat, 11 Jul 2015 05:46:34 -0400 (EDT) Received: by padck2 with SMTP id ck2so16101722pad.0 for ; Sat, 11 Jul 2015 02:46:34 -0700 (PDT) Received: from mail-pd0-x235.google.com (mail-pd0-x235.google.com. [2607:f8b0:400e:c02::235]) by mx.google.com with ESMTPS id r11si18536272pdj.220.2015.07.11.02.46.33 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sat, 11 Jul 2015 02:46:33 -0700 (PDT) Received: by pdrg1 with SMTP id g1so65099582pdr.2 for ; Sat, 11 Jul 2015 02:46:33 -0700 (PDT) From: Sergey Senozhatsky Subject: [PATCH 2/3] zram: make compact a read-write sysfs node Date: Sat, 11 Jul 2015 18:45:31 +0900 Message-Id: <1436607932-7116-3-git-send-email-sergey.senozhatsky@gmail.com> In-Reply-To: <1436607932-7116-1-git-send-email-sergey.senozhatsky@gmail.com> References: <1436607932-7116-1-git-send-email-sergey.senozhatsky@gmail.com> Sender: owner-linux-mm@kvack.org List-ID: To: Minchan Kim Cc: Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Sergey Senozhatsky , Sergey Senozhatsky Change zram's `compact' sysfs node to be a read-write attribute. Write triggers zsmalloc compaction, just as before, read returns the number of pages that zsmalloc can potentially compact. User space now has a chance to estimate possible compaction memory savings and avoid unnecessary compactions. Example: if [ `cat /sys/block/zram/compact` -gt 10 ]; then echo 1 > /sys/block/zram/compact; fi Signed-off-by: Sergey Senozhatsky --- Documentation/ABI/testing/sysfs-block-zram | 7 ++++--- Documentation/blockdev/zram.txt | 4 +++- drivers/block/zram/zram_drv.c | 16 +++++++++++++++- 3 files changed, 22 insertions(+), 5 deletions(-) diff --git a/Documentation/ABI/testing/sysfs-block-zram b/Documentation/ABI/testing/sysfs-block-zram index 2e69e83..0093998 100644 --- a/Documentation/ABI/testing/sysfs-block-zram +++ b/Documentation/ABI/testing/sysfs-block-zram @@ -146,9 +146,10 @@ What: /sys/block/zram/compact Date: August 2015 Contact: Minchan Kim Description: - The compact file is write-only and trigger compaction for - allocator zrm uses. The allocator moves some objects so that - it could free fragment space. + The compact file is read/write. Write triggers underlying + allocator's memory compaction, which may result in memory + savings. Read returns the number of pages that compaction + can potentially (but not guaranteed to) free. What: /sys/block/zram/io_stat Date: August 2015 diff --git a/Documentation/blockdev/zram.txt b/Documentation/blockdev/zram.txt index 62435bb..1854f62 100644 --- a/Documentation/blockdev/zram.txt +++ b/Documentation/blockdev/zram.txt @@ -146,7 +146,9 @@ mem_limit RW the maximum amount of memory ZRAM can use to store the compressed data pages_compacted RO the number of pages freed during compaction (available only via zram/mm_stat node) -compact WO trigger memory compaction +compact RW write triggers memory compaction, read shows how many + pages can potentially (but not necessarily will) be + compacted WARNING ======= diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index f5ef9e0..def9b8a 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -404,6 +404,20 @@ static ssize_t compact_store(struct device *dev, return len; } +static ssize_t compact_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + struct zram *zram = dev_to_zram(dev); + unsigned long num_pages = 0; + + down_read(&zram->init_lock); + if (init_done(zram)) + num_pages = zs_pages_to_compact(zram->meta->mem_pool); + up_read(&zram->init_lock); + + return scnprintf(buf, PAGE_SIZE, "%lu\n", num_pages); +} + static ssize_t io_stat_show(struct device *dev, struct device_attribute *attr, char *buf) { @@ -1145,7 +1159,7 @@ static const struct block_device_operations zram_devops = { .owner = THIS_MODULE }; -static DEVICE_ATTR_WO(compact); +static DEVICE_ATTR_RW(compact); static DEVICE_ATTR_RW(disksize); static DEVICE_ATTR_RO(initstate); static DEVICE_ATTR_WO(reset); -- 2.4.5 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org