Messages in this thread | | | Date | Tue, 14 Jan 2014 13:15:10 +0100 | From | Jerome Marchand <> | Subject | Re: [PATCH 3/3] zram: rework reported to end-user zram statistics |
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On 01/14/2014 11:57 AM, Sergey Senozhatsky wrote: > > Hello Jerome, > > On (01/14/14 11:38), Jerome Marchand wrote: >> On 01/14/2014 10:37 AM, Sergey Senozhatsky wrote: >>> 1) Introduce ZRAM_ATTR_RO macro to generate zram atomic64_t stats >>> `show' functions and reduce code duplication. >>> >>> 2) Account and report back to user numbers of failed READ and WRITE >>> operations. >>> >>> 3) Remove `good' and `bad' compressed sub-requests stats. RW request may >>> cause a number of RW sub-requests. zram used to account `good' compressed >>> sub-queries (with compressed size less than 50% of original size), `bad' >>> compressed sub-queries (with compressed size greater that 75% of original >>> size), leaving sub-requests with compression size between 50% and 75% of >>> original size not accounted and not reported. >> >> That's weird: good/bad_compress are accounted, but it seems to me that >> they are to never used in any way. If so, there is indeed no reason to >> keep them. >> >> >>> Account each sub-request >>> compression size so we can calculate real device compression ratio. >> >> Your patch doesn't change the way pages_stored and compr[essed]_size >> are accounted. What does your patch change that allow us to calculate >> the "real" compression ratio? > > we have compressed size, number of stored pages and reported by zs pool > (as a zram memory_used attr) number of bytes used > > u64 zs_get_total_size_bytes(struct zs_pool *pool) > { > int i; > u64 npages = 0; > > for (i = 0; i < ZS_SIZE_CLASSES; i++) > npages += pool->size_class[i].pages_allocated; > > return npages << PAGE_SHIFT; > } > > looks enough to calculate device overall data compression ratio.
Yes. But don't we have all that already without your patch applied? What does this patch change?
> > -ss > >>> >>> 4) reported zram stats: >>> - num_writes -- number of writes >>> - num_reads -- number of reads >>> - pages_stored -- number of pages currently stored >>> - compressed_size -- compressed size of pages stored >> >> Wouldn't it be more practical to report the original and compressed >> data sizes using the same units as it is currently done? >> > > sorry, not sure I understand.
Currently users have access to orig_data_size and compr_data_size, both in bytes. With your patch, they have access to pages_stored in pages and compressed_size in bytes. I find the current set more practical.
Jerome
> >> Jerome >> >>> - pages_zero -- number of zero filled pages >>> - failed_read -- number of failed reads >>> - failed_writes -- can happen when memory is too low >>> - invalid_io -- non-page-aligned I/O requests >>> - notify_free -- number of swap slot free notifications >>> - memory_used -- zs pool zs_get_total_size_bytes() >>> >>> Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> >>> --- >>> drivers/block/zram/zram_drv.c | 167 ++++++++++++------------------------------ >>> drivers/block/zram/zram_drv.h | 17 ++--- >>> 2 files changed, 54 insertions(+), 130 deletions(-) >>> >>> diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c >>> index 2a7682c..8bddaff 100644 >>> --- a/drivers/block/zram/zram_drv.c >>> +++ b/drivers/block/zram/zram_drv.c >>> @@ -42,6 +42,17 @@ static struct zram *zram_devices; >>> /* Module params (documentation at end) */ >>> static unsigned int num_devices = 1; >>> >>> +#define ZRAM_ATTR_RO(name) \ >>> +static ssize_t zram_attr_##name##_show(struct device *d, \ >>> + struct device_attribute *attr, char *b) \ >>> +{ \ >>> + struct zram *zram = dev_to_zram(d); \ >>> + return sprintf(b, "%llu\n", \ >>> + (u64)atomic64_read(&zram->stats.name)); \ >>> +} \ >>> +static struct device_attribute dev_attr_##name = \ >>> + __ATTR(name, S_IRUGO, zram_attr_##name##_show, NULL); >>> + >>> static inline int init_done(struct zram *zram) >>> { >>> return zram->meta != NULL; >>> @@ -52,97 +63,36 @@ static inline struct zram *dev_to_zram(struct device *dev) >>> return (struct zram *)dev_to_disk(dev)->private_data; >>> } >>> >>> -static ssize_t disksize_show(struct device *dev, >>> - struct device_attribute *attr, char *buf) >>> -{ >>> - struct zram *zram = dev_to_zram(dev); >>> - >>> - return sprintf(buf, "%llu\n", zram->disksize); >>> -} >>> - >>> -static ssize_t initstate_show(struct device *dev, >>> - struct device_attribute *attr, char *buf) >>> -{ >>> - struct zram *zram = dev_to_zram(dev); >>> - >>> - return sprintf(buf, "%u\n", init_done(zram)); >>> -} >>> - >>> -static ssize_t num_reads_show(struct device *dev, >>> - struct device_attribute *attr, char *buf) >>> -{ >>> - struct zram *zram = dev_to_zram(dev); >>> - >>> - return sprintf(buf, "%llu\n", >>> - (u64)atomic64_read(&zram->stats.num_reads)); >>> -} >>> - >>> -static ssize_t num_writes_show(struct device *dev, >>> - struct device_attribute *attr, char *buf) >>> -{ >>> - struct zram *zram = dev_to_zram(dev); >>> - >>> - return sprintf(buf, "%llu\n", >>> - (u64)atomic64_read(&zram->stats.num_writes)); >>> -} >>> - >>> -static ssize_t invalid_io_show(struct device *dev, >>> - struct device_attribute *attr, char *buf) >>> -{ >>> - struct zram *zram = dev_to_zram(dev); >>> - >>> - return sprintf(buf, "%llu\n", >>> - (u64)atomic64_read(&zram->stats.invalid_io)); >>> -} >>> - >>> -static ssize_t notify_free_show(struct device *dev, >>> - struct device_attribute *attr, char *buf) >>> -{ >>> - struct zram *zram = dev_to_zram(dev); >>> - >>> - return sprintf(buf, "%llu\n", >>> - (u64)atomic64_read(&zram->stats.notify_free)); >>> -} >>> - >>> -static ssize_t zero_pages_show(struct device *dev, >>> - struct device_attribute *attr, char *buf) >>> -{ >>> - struct zram *zram = dev_to_zram(dev); >>> - >>> - return sprintf(buf, "%u\n", atomic_read(&zram->stats.pages_zero)); >>> -} >>> - >>> -static ssize_t orig_data_size_show(struct device *dev, >>> +static ssize_t memory_used_show(struct device *dev, >>> struct device_attribute *attr, char *buf) >>> { >>> + u64 val = 0; >>> struct zram *zram = dev_to_zram(dev); >>> + struct zram_meta *meta = zram->meta; >>> >>> - return sprintf(buf, "%llu\n", >>> - (u64)(atomic_read(&zram->stats.pages_stored)) << PAGE_SHIFT); >>> + down_read(&zram->init_lock); >>> + if (init_done(zram)) >>> + val = zs_get_total_size_bytes(meta->mem_pool); >>> + up_read(&zram->init_lock); >>> + return sprintf(buf, "%llu\n", val); >>> } >>> >>> -static ssize_t compr_data_size_show(struct device *dev, >>> +static ssize_t disksize_show(struct device *dev, >>> struct device_attribute *attr, char *buf) >>> { >>> struct zram *zram = dev_to_zram(dev); >>> - >>> - return sprintf(buf, "%llu\n", >>> - (u64)atomic64_read(&zram->stats.compr_size)); >>> + return sprintf(buf, "%llu\n", zram->disksize); >>> } >>> >>> -static ssize_t mem_used_total_show(struct device *dev, >>> +static ssize_t initstate_show(struct device *dev, >>> struct device_attribute *attr, char *buf) >>> { >>> - u64 val = 0; >>> + u32 val = 0; >>> struct zram *zram = dev_to_zram(dev); >>> - struct zram_meta *meta = zram->meta; >>> - >>> down_read(&zram->init_lock); >>> - if (init_done(zram)) >>> - val = zs_get_total_size_bytes(meta->mem_pool); >>> + val = init_done(zram); >>> up_read(&zram->init_lock); >>> - >>> - return sprintf(buf, "%llu\n", val); >>> + return sprintf(buf, "%u\n", val); >>> } >>> >>> /* flag operations needs meta->tb_lock */ >>> @@ -293,7 +243,6 @@ static void zram_free_page(struct zram *zram, size_t index) >>> { >>> struct zram_meta *meta = zram->meta; >>> unsigned long handle = meta->table[index].handle; >>> - u16 size = meta->table[index].size; >>> >>> if (unlikely(!handle)) { >>> /* >>> @@ -302,21 +251,15 @@ static void zram_free_page(struct zram *zram, size_t index) >>> */ >>> if (zram_test_flag(meta, index, ZRAM_ZERO)) { >>> zram_clear_flag(meta, index, ZRAM_ZERO); >>> - atomic_dec(&zram->stats.pages_zero); >>> + atomic64_dec(&zram->stats.pages_zero); >>> } >>> return; >>> } >>> >>> - if (unlikely(size > max_zpage_size)) >>> - atomic_dec(&zram->stats.bad_compress); >>> - >>> zs_free(meta->mem_pool, handle); >>> >>> - if (size <= PAGE_SIZE / 2) >>> - atomic_dec(&zram->stats.good_compress); >>> - >>> - atomic64_sub(meta->table[index].size, &zram->stats.compr_size); >>> - atomic_dec(&zram->stats.pages_stored); >>> + atomic64_sub(meta->table[index].size, &zram->stats.compressed_size); >>> + atomic64_dec(&zram->stats.pages_stored); >>> >>> meta->table[index].handle = 0; >>> meta->table[index].size = 0; >>> @@ -362,7 +305,7 @@ static int zram_decompress_page(struct zram *zram, char *mem, u32 index) >>> static int zram_bvec_read(struct zram *zram, struct bio_vec *bvec, >>> u32 index, int offset, struct bio *bio) >>> { >>> - int ret; >>> + int ret = -EINVAL; >>> struct page *page; >>> unsigned char *user_mem, *uncmem = NULL; >>> struct zram_meta *meta = zram->meta; >>> @@ -406,6 +349,8 @@ out_cleanup: >>> kunmap_atomic(user_mem); >>> if (is_partial_io(bvec)) >>> kfree(uncmem); >>> + if (ret) >>> + atomic64_inc(&zram->stats.failed_reads); >>> return ret; >>> } >>> >>> @@ -459,7 +404,7 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index, >>> zram_set_flag(meta, index, ZRAM_ZERO); >>> write_unlock(&zram->meta->tb_lock); >>> >>> - atomic_inc(&zram->stats.pages_zero); >>> + atomic64_inc(&zram->stats.pages_zero); >>> ret = 0; >>> goto out; >>> } >>> @@ -478,7 +423,6 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index, >>> } >>> >>> if (unlikely(clen > max_zpage_size)) { >>> - atomic_inc(&zram->stats.bad_compress); >>> clen = PAGE_SIZE; >>> src = NULL; >>> if (is_partial_io(bvec)) >>> @@ -516,11 +460,8 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index, >>> write_unlock(&zram->meta->tb_lock); >>> >>> /* Update stats */ >>> - atomic64_add(clen, &zram->stats.compr_size); >>> - atomic_inc(&zram->stats.pages_stored); >>> - if (clen <= PAGE_SIZE / 2) >>> - atomic_inc(&zram->stats.good_compress); >>> - >>> + atomic64_add(clen, &zram->stats.compressed_size); >>> + atomic64_inc(&zram->stats.pages_stored); >>> out: >>> if (locked) >>> mutex_unlock(&meta->buffer_lock); >>> @@ -586,23 +527,8 @@ static void zram_reset_device(struct zram *zram, bool reset_capacity) >>> >>> static void zram_init_device(struct zram *zram, struct zram_meta *meta) >>> { >>> - if (zram->disksize > 2 * (totalram_pages << PAGE_SHIFT)) { >>> - pr_info( >>> - "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.\n" >>> - "\tMemory Size: %lu kB\n" >>> - "\tSize you selected: %llu kB\n" >>> - "Continuing anyway ...\n", >>> - (totalram_pages << PAGE_SHIFT) >> 10, zram->disksize >> 10 >>> - ); >>> - } >>> - >>> /* zram devices sort of resembles non-rotational disks */ >>> queue_flag_set_unlocked(QUEUE_FLAG_NONROT, zram->disk->queue); >>> - >>> zram->meta = meta; >>> pr_debug("Initialization done!\n"); >>> } >>> @@ -774,14 +700,15 @@ static DEVICE_ATTR(disksize, S_IRUGO | S_IWUSR, >>> disksize_show, disksize_store); >>> static DEVICE_ATTR(initstate, S_IRUGO, initstate_show, NULL); >>> static DEVICE_ATTR(reset, S_IWUSR, NULL, reset_store); >>> -static DEVICE_ATTR(num_reads, S_IRUGO, num_reads_show, NULL); >>> -static DEVICE_ATTR(num_writes, S_IRUGO, num_writes_show, NULL); >>> -static DEVICE_ATTR(invalid_io, S_IRUGO, invalid_io_show, NULL); >>> -static DEVICE_ATTR(notify_free, S_IRUGO, notify_free_show, NULL); >>> -static DEVICE_ATTR(zero_pages, S_IRUGO, zero_pages_show, NULL); >>> -static DEVICE_ATTR(orig_data_size, S_IRUGO, orig_data_size_show, NULL); >>> -static DEVICE_ATTR(compr_data_size, S_IRUGO, compr_data_size_show, NULL); >>> -static DEVICE_ATTR(mem_used_total, S_IRUGO, mem_used_total_show, NULL); >>> +static DEVICE_ATTR(memory_used, S_IRUGO, memory_used_show, NULL); >>> + >>> +ZRAM_ATTR_RO(num_reads); >>> +ZRAM_ATTR_RO(num_writes); >>> +ZRAM_ATTR_RO(pages_stored); >>> +ZRAM_ATTR_RO(invalid_io); >>> +ZRAM_ATTR_RO(notify_free); >>> +ZRAM_ATTR_RO(pages_zero); >>> +ZRAM_ATTR_RO(compressed_size); >>> >>> static struct attribute *zram_disk_attrs[] = { >>> &dev_attr_disksize.attr, >>> @@ -789,12 +716,12 @@ static struct attribute *zram_disk_attrs[] = { >>> &dev_attr_reset.attr, >>> &dev_attr_num_reads.attr, >>> &dev_attr_num_writes.attr, >>> + &dev_attr_pages_stored.attr, >>> &dev_attr_invalid_io.attr, >>> &dev_attr_notify_free.attr, >>> - &dev_attr_zero_pages.attr, >>> - &dev_attr_orig_data_size.attr, >>> - &dev_attr_compr_data_size.attr, >>> - &dev_attr_mem_used_total.attr, >>> + &dev_attr_pages_zero.attr, >>> + &dev_attr_compressed_size.attr, >>> + &dev_attr_memory_used.attr, >>> NULL, >>> }; >>> >>> diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h >>> index e81e9cd..277023d 100644 >>> --- a/drivers/block/zram/zram_drv.h >>> +++ b/drivers/block/zram/zram_drv.h >>> @@ -64,22 +64,19 @@ enum zram_pageflags { >>> struct table { >>> unsigned long handle; >>> u16 size; /* object size (excluding header) */ >>> - u8 count; /* object ref count (not yet used) */ >>> - u8 flags; >>> + u16 flags; >>> } __aligned(4); >>> >>> struct zram_stats { >>> - atomic64_t compr_size; /* compressed size of pages stored */ >>> - atomic64_t num_reads; /* failed + successful */ >>> - atomic64_t num_writes; /* --do-- */ >>> - atomic64_t failed_reads; /* should NEVER! happen */ >>> + atomic64_t num_writes; /* number of writes */ >>> + atomic64_t num_reads; /* number of reads */ >>> + atomic64_t pages_stored; /* no. of pages currently stored */ >>> + atomic64_t compressed_size; /* compressed size of pages stored */ >>> + atomic64_t pages_zero; /* no. of zero filled pages */ >>> + atomic64_t failed_reads; /* no. of failed reads */ >>> atomic64_t failed_writes; /* can happen when memory is too low */ >>> atomic64_t invalid_io; /* non-page-aligned I/O requests */ >>> atomic64_t notify_free; /* no. of swap slot free notifications */ >>> - atomic_t pages_zero; /* no. of zero filled pages */ >>> - atomic_t pages_stored; /* no. of pages currently stored */ >>> - atomic_t good_compress; /* % of pages with compression ratio<=50% */ >>> - atomic_t bad_compress; /* % of pages with compression ratio>=75% */ >>> }; >>> >>> struct zram_meta { >>> >>
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