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Date: Mon, 6 Feb 2017 09:28:18 +0800 From: zhouxianrong <zhouxianrong@...wei.com> To: Minchan Kim <minchan@...nel.org> CC: <linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>, <akpm@...ux-foundation.org>, <sergey.senozhatsky@...il.com>, <willy@...radead.org>, <iamjoonsoo.kim@....com>, <ngupta@...are.org>, <Mi.Sophia.Wang@...wei.com>, <zhouxiyu@...wei.com>, <weidu.du@...wei.com>, <zhangshiming5@...wei.com>, <won.ho.park@...wei.com> Subject: Re: [PATCH] mm: extend zero pages to same element pages for zram On 2017/2/5 22:21, Minchan Kim wrote: > Hi zhouxianrong, > > On Fri, Feb 03, 2017 at 04:42:27PM +0800, zhouxianrong@...wei.com wrote: >> From: zhouxianrong <zhouxianrong@...wei.com> >> >> test result as listed below: >> >> zero pattern_char pattern_short pattern_int pattern_long total (unit) >> 162989 14454 3534 23516 2769 3294399 (page) >> >> statistics for the result: >> >> zero pattern_char pattern_short pattern_int pattern_long >> AVERAGE 0.745696298 0.085937175 0.015957701 0.131874915 0.020533911 >> STDEV 0.035623777 0.016892402 0.004454534 0.021657123 0.019420072 >> MAX 0.973813421 0.222222222 0.021409518 0.211812245 0.176512625 >> MIN 0.645431905 0.004634398 0 0 0 > > The description in old version was better for justifying same page merging > feature. > >> >> Signed-off-by: zhouxianrong <zhouxianrong@...wei.com> >> --- >> drivers/block/zram/zram_drv.c | 124 +++++++++++++++++++++++++++++++---------- >> drivers/block/zram/zram_drv.h | 11 ++-- >> 2 files changed, 103 insertions(+), 32 deletions(-) >> >> diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c >> index e5ab7d9..6a8c9c5 100644 >> --- a/drivers/block/zram/zram_drv.c >> +++ b/drivers/block/zram/zram_drv.c >> @@ -95,6 +95,17 @@ static void zram_clear_flag(struct zram_meta *meta, u32 index, >> meta->table[index].value &= ~BIT(flag); >> } >> >> +static inline void zram_set_element(struct zram_meta *meta, u32 index, >> + unsigned long element) >> +{ >> + meta->table[index].element = element; >> +} >> + >> +static inline void zram_clear_element(struct zram_meta *meta, u32 index) >> +{ >> + meta->table[index].element = 0; >> +} >> + >> static size_t zram_get_obj_size(struct zram_meta *meta, u32 index) >> { >> return meta->table[index].value & (BIT(ZRAM_FLAG_SHIFT) - 1); >> @@ -167,31 +178,78 @@ static inline void update_used_max(struct zram *zram, >> } while (old_max != cur_max); >> } >> >> -static bool page_zero_filled(void *ptr) >> +static inline void zram_fill_page(char *ptr, unsigned long value) >> +{ >> + int i; >> + unsigned long *page = (unsigned long *)ptr; >> + >> + if (likely(value == 0)) { >> + clear_page(ptr); >> + } else { >> + for (i = 0; i < PAGE_SIZE / sizeof(*page); i++) >> + page[i] = value; >> + } >> +} >> + >> +static inline void zram_fill_page_partial(char *ptr, unsigned int size, >> + unsigned long value) >> +{ >> + int i; >> + unsigned long *page; >> + >> + if (likely(value == 0)) { >> + memset(ptr, 0, size); >> + return; >> + } >> + >> + i = ((unsigned long)ptr) % sizeof(*page); >> + if (i) { >> + while (i < sizeof(*page)) { >> + *ptr++ = (value >> (i * 8)) & 0xff; >> + --size; >> + ++i; >> + } >> + } >> + > > I don't think we need this part because block layer works with sector > size or multiple times of it so it must be aligned unsigned long. > > > > > . > Minchan and Matthew Wilcox: 1. right, but users could open /dev/block/zram0 file and do any read operations. 2. about endian operation for long, the modification is trivial and low efficient. i have not better method. do you have any good idea for this? 3. the below should be modified. static inline bool zram_meta_get(struct zram *zram) @@ -495,11 +553,17 @@ static void zram_meta_free(struct zram_meta *meta, u64 disksize) /* Free all pages that are still in this zram device */ for (index = 0; index < num_pages; index++) { - unsigned long handle = meta->table[index].handle; + unsigned long handle; + + bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value); + handle = meta->table[index].handle; - if (!handle) + if (!handle || zram_test_flag(meta, index, ZRAM_SAME)) { + bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value); continue; + } + bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value); zs_free(meta->mem_pool, handle); } @@ -511,7 +575,7 @@ static void zram_meta_free(struct zram_meta *meta, u64 disksize) static struct zram_meta *zram_meta_alloc(char *pool_name, u64 disksize) { size_t num_pages; - struct zram_meta *meta = kmalloc(sizeof(*meta), GFP_KERNEL); + struct zram_meta *meta = kzalloc(sizeof(*meta), GFP_KERNEL);
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