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Jaegeuk Kim authored
Previously, we experience bio traces as follows when running simple sequential write test. f2fs_do_submit_bio: type = NODE, io = no sync, sector = 500104928, size = 4K f2fs_do_submit_bio: type = NODE, io = no sync, sector = 499922208, size = 368K f2fs_do_submit_bio: type = NODE, io = no sync, sector = 499914752, size = 140K -> total 512K The first one is to write an indirect node block, and the others are to write direct node blocks. The reason why there are two separate bios for direct node blocks is: 0. initial state ------------------ ------------------ | | |xxxxxxxx | ------------------ ------------------ 1. write 368K ------------------ ------------------ | | |xxxxxxxxWWWWWWWW| ------------------ ------------------ 2. write 140K ------------------ ------------------ |WWWWWWW | |xxxxxxxxWWWWWWWW| ------------------ ------------------ This is because f2fs_write_node_pages tries to write just 512K totally, so that we can lose the chance to merge more bios nicely. After this patch is applied, we can get the following bio traces. f2fs_do_submit_bio: type = NODE, io = no sync, sector = 500103168, size = 8K f2fs_do_submit_bio: type = NODE, io = no sync, sector = 500111368, size = 4K f2fs_do_submit_bio: type = NODE, io = no sync, sector = 500107272, size = 512K f2fs_do_submit_bio: type = NODE, io = no sync, sector = 500108296, size = 512K f2fs_do_submit_bio: type = NODE, io = no sync, sector = 500109320, size = 500K And finally, we can improve the sequential write performance, from 458.775 MB/s to 479.945 MB/s on SSD. Signed-off-by:
Jaegeuk Kim <jaegeuk.kim@samsung.com>
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