On Wed, Jul 6, 2017 at 10:49 AM, Sergey Senozhatsky wrote: > On (07/02/17 20:28), Seth Jennings wrote: >> On Sun, Jul 2, 2017 at 9:19 AM, Srividya Desireddy >> > Zswap is a cache which compresses the pages that are being swapped out >> > and stores them into a dynamically allocated RAM-based memory pool. >> > Experiments have shown that around 10-20% of pages stored in zswap >> > are zero-filled pages (i.e. contents of the page are all zeros), but >> > these pages are handled as normal pages by compressing and allocating >> > memory in the pool. >> >> I am somewhat surprised that this many anon pages are zero filled. >> >> If this is true, then maybe we should consider solving this at the >> swap level in general, as we can de-dup zero pages in all swap >> devices, not just zswap. >> >> That being said, this is a fair small change and I don't see anything >> objectionable. However, I do think the better solution would be to do > this at a higher level. > Thank you for your suggestion. It is a better solution to handle zero-filled pages before swapping-out to zswap. Since, Zram is already handles Zero pages internally, I considered to handle within Zswap. In a long run, we can work on it to commonly handle zero-filled anon pages. > zero-filled pages are just 1 case. in general, it's better > to handle pages that are memset-ed with the same value (e.g. > memset(page, 0x01, page_size)). which includes, but not > limited to, 0x00. zram does it. > > -ss It is a good solution to extend zero-filled pages handling to same value pages. I will work on to identify the percentage of same value pages excluding zero-filled pages in Zswap and will get back. - Srividya -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
