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Sun, 02 Mar 2025 18:24:54 -0800 (PST) Received: from localhost ([2401:fa00:8f:203:1513:4f61:a4d3:b418]) by smtp.gmail.com with UTF8SMTPSA id d9443c01a7336-223504c5cc6sm67129725ad.112.2025.03.02.18.24.52 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 02 Mar 2025 18:24:54 -0800 (PST) From: Sergey Senozhatsky To: Andrew Morton Cc: Yosry Ahmed , Hillf Danton , Kairui Song , Sebastian Andrzej Siewior , Minchan Kim , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Sergey Senozhatsky Subject: [PATCH v10 04/19] zram: remove max_comp_streams device attr Date: Mon, 3 Mar 2025 11:03:13 +0900 Message-ID: <20250303022425.285971-5-senozhatsky@chromium.org> X-Mailer: git-send-email 2.48.1.711.g2feabab25a-goog In-Reply-To: <20250303022425.285971-1-senozhatsky@chromium.org> References: <20250303022425.285971-1-senozhatsky@chromium.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" max_comp_streams device attribute has been defunct since May 2016 when zram switched to per-CPU compression streams, remove it. Signed-off-by: Sergey Senozhatsky --- Documentation/ABI/testing/sysfs-block-zram | 8 ----- Documentation/admin-guide/blockdev/zram.rst | 36 ++++++--------------- drivers/block/zram/zram_drv.c | 23 ------------- 3 files changed, 10 insertions(+), 57 deletions(-) diff --git a/Documentation/ABI/testing/sysfs-block-zram b/Documentation/ABI= /testing/sysfs-block-zram index 1ef69e0271f9..36c57de0a10a 100644 --- a/Documentation/ABI/testing/sysfs-block-zram +++ b/Documentation/ABI/testing/sysfs-block-zram @@ -22,14 +22,6 @@ Description: device. The reset operation frees all the memory associated with this device. =20 -What: /sys/block/zram/max_comp_streams -Date: February 2014 -Contact: Sergey Senozhatsky -Description: - The max_comp_streams file is read-write and specifies the - number of backend's zcomp_strm compression streams (number of - concurrent compress operations). - What: /sys/block/zram/comp_algorithm Date: February 2014 Contact: Sergey Senozhatsky diff --git a/Documentation/admin-guide/blockdev/zram.rst b/Documentation/ad= min-guide/blockdev/zram.rst index 714a5171bfc0..7ad4c86f8258 100644 --- a/Documentation/admin-guide/blockdev/zram.rst +++ b/Documentation/admin-guide/blockdev/zram.rst @@ -54,7 +54,7 @@ The list of possible return codes: If you use 'echo', the returned value is set by the 'echo' utility, and, in general case, something like:: =20 - echo 3 > /sys/block/zram0/max_comp_streams + echo foo > /sys/block/zram0/comp_algorithm if [ $? -ne 0 ]; then handle_error fi @@ -73,21 +73,7 @@ This creates 4 devices: /dev/zram{0,1,2,3} num_devices parameter is optional and tells zram how many devices should be pre-created. Default: 1. =20 -2) Set max number of compression streams -=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D - -Regardless of the value passed to this attribute, ZRAM will always -allocate multiple compression streams - one per online CPU - thus -allowing several concurrent compression operations. The number of -allocated compression streams goes down when some of the CPUs -become offline. There is no single-compression-stream mode anymore, -unless you are running a UP system or have only 1 CPU online. - -To find out how many streams are currently available:: - - cat /sys/block/zram0/max_comp_streams - -3) Select compression algorithm +2) Select compression algorithm =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D =20 Using comp_algorithm device attribute one can see available and @@ -107,7 +93,7 @@ Examples:: For the time being, the `comp_algorithm` content shows only compression algorithms that are supported by zram. =20 -4) Set compression algorithm parameters: Optional +3) Set compression algorithm parameters: Optional =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D =20 Compression algorithms may support specific parameters which can be @@ -138,7 +124,7 @@ better the compression ratio, it even can take negative= s values for some algorithms), for other algorithms `level` is acceleration level (the higher the value the lower the compression ratio). =20 -5) Set Disksize +4) Set Disksize =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D =20 Set disk size by writing the value to sysfs node 'disksize'. @@ -158,7 +144,7 @@ There is little point creating a zram of greater than t= wice the size of memory since we expect a 2:1 compression ratio. Note that zram uses about 0.1% of= the size of the disk when not in use so a huge zram is wasteful. =20 -6) Set memory limit: Optional +5) Set memory limit: Optional =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D =20 Set memory limit by writing the value to sysfs node 'mem_limit'. @@ -177,7 +163,7 @@ Examples:: # To disable memory limit echo 0 > /sys/block/zram0/mem_limit =20 -7) Activate +6) Activate =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D =20 :: @@ -188,7 +174,7 @@ Examples:: mkfs.ext4 /dev/zram1 mount /dev/zram1 /tmp =20 -8) Add/remove zram devices +7) Add/remove zram devices =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D =20 zram provides a control interface, which enables dynamic (on-demand) device @@ -208,7 +194,7 @@ execute:: =20 echo X > /sys/class/zram-control/hot_remove =20 -9) Stats +8) Stats =3D=3D=3D=3D=3D=3D=3D=3D =20 Per-device statistics are exported as various nodes under /sys/block/zram<= id>/ @@ -228,8 +214,6 @@ mem_limit WO specifies the maximum amount of m= emory ZRAM can writeback_limit WO specifies the maximum amount of write IO zram can write out to backing device as 4KB unit writeback_limit_enable RW show and set writeback_limit feature -max_comp_streams RW the number of possible concurrent compress - operations comp_algorithm RW show and change the compression algorithm algorithm_params WO setup compression algorithm parameters compact WO trigger memory compaction @@ -310,7 +294,7 @@ a single line of text and contains the following stats = separated by whitespace: Unit: 4K bytes =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D =20 -10) Deactivate +9) Deactivate =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D =20 :: @@ -318,7 +302,7 @@ a single line of text and contains the following stats = separated by whitespace: swapoff /dev/zram0 umount /dev/zram1 =20 -11) Reset +10) Reset =3D=3D=3D=3D=3D=3D=3D=3D=3D =20 Write any positive value to 'reset' sysfs node:: diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index 248dab7cc7f4..93cedc60ac16 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -1103,27 +1103,6 @@ static void zram_debugfs_register(struct zram *zram)= {}; static void zram_debugfs_unregister(struct zram *zram) {}; #endif =20 -/* - * We switched to per-cpu streams and this attr is not needed anymore. - * However, we will keep it around for some time, because: - * a) we may revert per-cpu streams in the future - * b) it's visible to user space and we need to follow our 2 years - * retirement rule; but we already have a number of 'soon to be - * altered' attrs, so max_comp_streams need to wait for the next - * layoff cycle. - */ -static ssize_t max_comp_streams_show(struct device *dev, - struct device_attribute *attr, char *buf) -{ - return scnprintf(buf, PAGE_SIZE, "%d\n", num_online_cpus()); -} - -static ssize_t max_comp_streams_store(struct device *dev, - struct device_attribute *attr, const char *buf, size_t len) -{ - return len; -} - static void comp_algorithm_set(struct zram *zram, u32 prio, const char *al= g) { /* Do not free statically defined compression algorithms */ @@ -2540,7 +2519,6 @@ static DEVICE_ATTR_WO(reset); static DEVICE_ATTR_WO(mem_limit); static DEVICE_ATTR_WO(mem_used_max); static DEVICE_ATTR_WO(idle); -static DEVICE_ATTR_RW(max_comp_streams); static DEVICE_ATTR_RW(comp_algorithm); #ifdef CONFIG_ZRAM_WRITEBACK static DEVICE_ATTR_RW(backing_dev); @@ -2562,7 +2540,6 @@ static struct attribute *zram_disk_attrs[] =3D { &dev_attr_mem_limit.attr, &dev_attr_mem_used_max.attr, &dev_attr_idle.attr, - &dev_attr_max_comp_streams.attr, &dev_attr_comp_algorithm.attr, #ifdef CONFIG_ZRAM_WRITEBACK &dev_attr_backing_dev.attr, --=20 2.48.1.711.g2feabab25a-goog