From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753836AbbGKJqh (ORCPT ); Sat, 11 Jul 2015 05:46:37 -0400 Received: from mail-pd0-f172.google.com ([209.85.192.172]:36136 "EHLO mail-pd0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753761AbbGKJqe (ORCPT ); Sat, 11 Jul 2015 05:46:34 -0400 From: Sergey Senozhatsky To: Minchan Kim Cc: Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Sergey Senozhatsky , 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> X-Mailer: git-send-email 2.4.5 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: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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