On Fri, Jan 17, 2014 at 02:04:17PM +0300, Sergey Senozhatsky wrote: > Add compressor device attr that allows to list and select > compression algorithms. > > Define and make available for selection LZ4 compressor ops. > > usage example: > List available compression algorithms (currently selected > one is LZO): > cat /sys/block/zram0/compressor > <lzo> lz4 > > Change compression algorithm to LZ4: > echo lz4 > /sys/block/zram0/compressor > cat /sys/block/zram0/compressor > lzo <lz4>
Interface looks good to me. > > Update documentation with "Select compression algorithm" section > > Signed-off-by: Sergey Senozhatsky <sergey.senozhat...@gmail.com> > --- > Documentation/blockdev/zram.txt | 23 ++++++++++++++++----- > drivers/block/zram/Kconfig | 2 ++ > drivers/block/zram/zram_drv.c | 46 > +++++++++++++++++++++++++++++++++++++---- > 3 files changed, 62 insertions(+), 9 deletions(-) > > diff --git a/Documentation/blockdev/zram.txt b/Documentation/blockdev/zram.txt > index 393541be..af90d29 100644 > --- a/Documentation/blockdev/zram.txt > +++ b/Documentation/blockdev/zram.txt > @@ -21,7 +21,20 @@ Following shows a typical sequence of steps for using zram. > This creates 4 devices: /dev/zram{0,1,2,3} > (num_devices parameter is optional. Default: 1) > > -2) Set Disksize > +2) Select compression algorithm > +'compressor' sysfs node allows to see available, currently used > +and change compression algorithms. > +In order to list available compression algorithms (currently selected > +one is LZO): > + cat /sys/block/zram0/compressor > + <lzo> lz4 > + > +Change compression algorithm to LZ4: > + echo lz4 > /sys/block/zram0/compressor > + cat /sys/block/zram0/compressor > + lzo <lz4> > + > +3) Set Disksize > Set disk size by writing the value to sysfs node 'disksize'. > The value can be either in bytes or you can use mem suffixes. > Examples: > @@ -38,14 +51,14 @@ There is little point creating a zram of greater than > twice 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. > > -3) Activate: > +4) Activate: > mkswap /dev/zram0 > swapon /dev/zram0 > > mkfs.ext4 /dev/zram1 > mount /dev/zram1 /tmp > > -4) Stats: > +5) Stats: > Per-device statistics are exported as various nodes under > /sys/block/zram<id>/ > disksize > @@ -59,11 +72,11 @@ size of the disk when not in use so a huge zram is > wasteful. > compr_data_size > mem_used_total > > -5) Deactivate: > +6) Deactivate: > swapoff /dev/zram0 > umount /dev/zram1 > > -6) Reset: > +7) Reset: > Write any positive value to 'reset' sysfs node > echo 1 > /sys/block/zram0/reset > echo 1 > /sys/block/zram1/reset > diff --git a/drivers/block/zram/Kconfig b/drivers/block/zram/Kconfig > index 3450be8..09dacd6 100644 > --- a/drivers/block/zram/Kconfig > +++ b/drivers/block/zram/Kconfig > @@ -3,6 +3,8 @@ config ZRAM > depends on BLOCK && SYSFS && ZSMALLOC > select LZO_COMPRESS > select LZO_DECOMPRESS > + select LZ4_COMPRESS > + select LZ4_DECOMPRESS But user should select what kinds of compressor then want some user want only lzo while others want lzo, lz2 and zlib all. > default n > help > Creates virtual block devices called /dev/zramX (X = 0, 1, ...). > diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c > index 4f2c748..f1434f8 100644 > --- a/drivers/block/zram/zram_drv.c > +++ b/drivers/block/zram/zram_drv.c > @@ -31,6 +31,7 @@ > #include <linux/string.h> > #include <linux/vmalloc.h> > #include <linux/lzo.h> > +#include <linux/lz4.h> > > #include "zram_drv.h" > > @@ -47,6 +48,12 @@ static struct zram_compress_ops lzo_compressor = { > .decompress = lzo1x_decompress_safe, > }; > > +static struct zram_compress_ops lz4_compressor = { > + .workmem_sz = LZ4_MEM_COMPRESS, > + .compress = lz4_compress, > + .decompress = lz4_decompress_unknownoutputsize, > +}; > + > #define ZRAM_ATTR_RO(name) \ > static ssize_t zram_attr_##name##_show(struct device *d, \ > struct device_attribute *attr, char *b) \ > @@ -113,6 +120,34 @@ static ssize_t mem_used_total_show(struct device *dev, > return sprintf(buf, "%llu\n", val); > } > > +static ssize_t compressor_show(struct device *dev, > + struct device_attribute *attr, char *buf) > +{ > + struct zram *zram = dev_to_zram(dev); > + if (zram->ops == &lzo_compressor) > + return sprintf(buf, "<lzo> lz4\n"); > + return sprintf(buf, "lzo <lz4>\n"); > +} > + > +static ssize_t compressor_store(struct device *dev, > + struct device_attribute *attr, const char *buf, size_t len) > +{ > + struct zram *zram = dev_to_zram(dev); > + > + down_write(&zram->init_lock); > + if (init_done(zram)) { > + up_write(&zram->init_lock); > + pr_info("Cannot change compressor for initialized device\n"); > + return -EBUSY; > + } > + if (strncmp(buf, "lzo", 3) == 0) > + zram->ops = &lzo_compressor; > + else > + zram->ops = &lz4_compressor; > + up_write(&zram->init_lock); > + return len; > +} Changing compressow should be allowed only when zram was created or reset. IOW, there should be no datacompressed by old compressor in memory. > + > /* flag operations needs meta->tb_lock */ > static int zram_test_flag(struct zram_meta *meta, u32 index, > enum zram_pageflags flag) > @@ -285,7 +320,7 @@ static void zram_free_page(struct zram *zram, size_t > index) > > static int zram_decompress_page(struct zram *zram, char *mem, u32 index) > { > - int ret = LZO_E_OK; > + int ret = 0; > size_t clen = PAGE_SIZE; > unsigned char *cmem; > struct zram_meta *meta = zram->meta; > @@ -311,7 +346,7 @@ static int zram_decompress_page(struct zram *zram, char > *mem, u32 index) > read_unlock(&meta->tb_lock); > > /* Should NEVER happen. Return bio error if it does. */ > - if (unlikely(ret != LZO_E_OK)) { > + if (unlikely(ret)) { > pr_err("Decompression failed! err=%d, page=%u\n", ret, index); > atomic64_inc(&zram->stats.failed_reads); > return ret; > @@ -354,7 +389,7 @@ static int zram_bvec_read(struct zram *zram, struct > bio_vec *bvec, > > ret = zram_decompress_page(zram, uncmem, index); > /* Should NEVER happen. Return bio error if it does. */ > - if (unlikely(ret != LZO_E_OK)) > + if (unlikely(ret)) > goto out_cleanup; > > if (is_partial_io(bvec)) > @@ -433,7 +468,7 @@ static int zram_bvec_write(struct zram *zram, struct > bio_vec *bvec, u32 index, > uncmem = NULL; > } > > - if (unlikely(ret != LZO_E_OK)) { > + if (unlikely(ret)) { > pr_err("Compression failed! err=%d\n", ret); > goto out; > } > @@ -705,6 +740,8 @@ static DEVICE_ATTR(initstate, S_IRUGO, initstate_show, > NULL); > static DEVICE_ATTR(reset, S_IWUSR, NULL, reset_store); > static DEVICE_ATTR(orig_data_size, S_IRUGO, orig_data_size_show, NULL); > static DEVICE_ATTR(mem_used_total, S_IRUGO, mem_used_total_show, NULL); > +static DEVICE_ATTR(compressor, S_IRUGO | S_IWUSR, > + compressor_show, compressor_store); > > ZRAM_ATTR_RO(num_reads); > ZRAM_ATTR_RO(num_writes); > @@ -719,6 +756,7 @@ static struct attribute *zram_disk_attrs[] = { > &dev_attr_disksize.attr, > &dev_attr_initstate.attr, > &dev_attr_reset.attr, > + &dev_attr_compressor.attr, > &dev_attr_num_reads.attr, > &dev_attr_num_writes.attr, > &dev_attr_failed_reads.attr, > -- > 1.8.5.3.493.gb139ac2 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majord...@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- Kind regards, Minchan Kim -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/