On Sun, 27 Jan 2013, Shaohua Li wrote: > On Sat, Jan 26, 2013 at 01:40:55PM +0900, Kyungmin Park wrote: > > 5. SSD related optimization, mainly discard support. > > > > Now swap codes are based on each swap slots. it means it can't > > optimize discard feature since getting meaningful performance gain, it > > requires 2 pages at least. Of course it's based on eMMC. In case of > > SSD. it requires more pages to support discard. > > > > To address issue. I consider the batched discard approach used at filesystem. > > *Sometime* scan all empty slot and it issues discard continuous swap > > slots as many as possible. > > I posted a patch to make discard async before, which is almost good to me, > though we still discard a cluster. > http://marc.info/?l=linux-mm&m=135087309208120&w=2 Any reason why you point to 2012/10/22 patch rather than the 2012/11/19? Seeing this reminded me to take your 1/2 and 2/2 (of 11/19) out again and give them a fresh run - though they were easier to apply to 3.8-rc rather than mmotm with your locking changes, so it was 3.8-rc6 I tried. As I reported in private mail last year, I wish you'd remove the "buddy" from description of your 1/2 allocator, that just misled me; but I've not experienced any problem with the allocator, and I still like the direction you take with improving swap discard in 2/2. This time around I've not yet seen any "swap_free: Unused swap offset entry" messages (despite forgetting to include your later SWAP_MAP_BAD addition to __swap_duplicate() - I still haven't thought that through to be honest), but did again get the VM_BUG_ON(error == -EEXIST) in __add_to_swap_cache() called from add_to_swap() from shrink_page_list(). Since it came after 1.5 hours of load, I didn't give it much thought, and just went on to test other things, thinking I could easily reproduce it later; but have failed to do so in many hours since. Still trying. Hugh -- 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>