On 7/28/25 16:03, hanqi wrote: > 在 2025/7/28 15:38, Chao Yu 写道: > >> On 7/25/25 15:53, Qi Han wrote: >>> Jens has already completed the development of uncached buffered I/O >>> in git [1], and in f2fs, uncached buffered I/O read can be enabled >>> simply by setting the FOP_DONTCACHE flag in f2fs_file_operations. >> IIUC, we may suffer lock issue when we call pwritev(.. ,RWF_DONTCACHE)? >> as Jen mentioned in below path, right? >> >> soft-irq >> - folio_end_writeback() >> - filemap_end_dropbehind_write() >> - filemap_end_dropbehind() >> - folio_unmap_invalidate() >> - lock i_lock >> >> Thanks, > > That's how I understand it.
So I guess we need to wait for the support RWF_DONTCACHE on write path, unless you can walk around for write path in this patch. Thanks, > >>> I have been testing a use case locally, which aligns with Jens' test >>> case [2]. In the read scenario, using uncached buffer I/O results in >>> more stable read performance and a lower load on the background memory >>> reclaim thread (kswapd). So let's enable uncached buffer I/O reads on >>> F2FS. >>> >>> Read test data without using uncached buffer I/O: >>> reading bs 32768, uncached 0 >>> 1s: 1856MB/sec, MB=1856 >>> 2s: 1907MB/sec, MB=3763 >>> 3s: 1830MB/sec, MB=5594 >>> 4s: 1745MB/sec, MB=7333 >>> 5s: 1829MB/sec, MB=9162 >>> 6s: 1903MB/sec, MB=11075 >>> 7s: 1878MB/sec, MB=12942 >>> 8s: 1763MB/sec, MB=14718 >>> 9s: 1845MB/sec, MB=16549 >>> 10s: 1915MB/sec, MB=18481 >>> 11s: 1831MB/sec, MB=20295 >>> 12s: 1750MB/sec, MB=22066 >>> 13s: 1787MB/sec, MB=23832 >>> 14s: 1913MB/sec, MB=25769 >>> 15s: 1898MB/sec, MB=27668 >>> 16s: 1795MB/sec, MB=29436 >>> 17s: 1812MB/sec, MB=31248 >>> 18s: 1890MB/sec, MB=33139 >>> 19s: 1880MB/sec, MB=35020 >>> 20s: 1754MB/sec, MB=36810 >>> >>> 08:36:26 UID PID %usr %system %guest %wait %CPU CPU >>> Command >>> 08:36:27 0 93 0.00 0.00 0.00 0.00 0.00 7 >>> kswapd0 >>> 08:36:28 0 93 0.00 0.00 0.00 0.00 0.00 7 >>> kswapd0 >>> 08:36:29 0 93 0.00 0.00 0.00 0.00 0.00 7 >>> kswapd0 >>> 08:36:30 0 93 0.00 56.00 0.00 0.00 56.00 7 >>> kswapd0 >>> 08:36:31 0 93 0.00 73.00 0.00 0.00 73.00 7 >>> kswapd0 >>> 08:36:32 0 93 0.00 83.00 0.00 0.00 83.00 7 >>> kswapd0 >>> 08:36:33 0 93 0.00 75.00 0.00 0.00 75.00 7 >>> kswapd0 >>> 08:36:34 0 93 0.00 81.00 0.00 0.00 81.00 7 >>> kswapd0 >>> 08:36:35 0 93 0.00 54.00 0.00 1.00 54.00 2 >>> kswapd0 >>> 08:36:36 0 93 0.00 61.00 0.00 0.00 61.00 0 >>> kswapd0 >>> 08:36:37 0 93 0.00 68.00 0.00 0.00 68.00 7 >>> kswapd0 >>> 08:36:38 0 93 0.00 53.00 0.00 0.00 53.00 2 >>> kswapd0 >>> 08:36:39 0 93 0.00 82.00 0.00 0.00 82.00 7 >>> kswapd0 >>> 08:36:40 0 93 0.00 77.00 0.00 0.00 77.00 1 >>> kswapd0 >>> 08:36:41 0 93 0.00 74.00 0.00 1.00 74.00 7 >>> kswapd0 >>> 08:36:42 0 93 0.00 71.00 0.00 0.00 71.00 7 >>> kswapd0 >>> 08:36:43 0 93 0.00 78.00 0.00 0.00 78.00 7 >>> kswapd0 >>> 08:36:44 0 93 0.00 85.00 0.00 0.00 85.00 7 >>> kswapd0 >>> 08:36:45 0 93 0.00 83.00 0.00 0.00 83.00 7 >>> kswapd0 >>> 08:36:46 0 93 0.00 70.00 0.00 0.00 70.00 7 >>> kswapd0 >>> 08:36:47 0 93 0.00 78.00 0.00 1.00 78.00 2 >>> kswapd0 >>> 08:36:48 0 93 0.00 81.00 0.00 0.00 81.00 3 >>> kswapd0 >>> 08:36:49 0 93 0.00 54.00 0.00 0.00 54.00 7 >>> kswapd0 >>> 08:36:50 0 93 0.00 76.00 0.00 0.00 76.00 1 >>> kswapd0 >>> 08:36:51 0 93 0.00 75.00 0.00 0.00 75.00 0 >>> kswapd0 >>> 08:36:52 0 93 0.00 73.00 0.00 0.00 73.00 7 >>> kswapd0 >>> 08:36:53 0 93 0.00 61.00 0.00 1.00 61.00 7 >>> kswapd0 >>> 08:36:54 0 93 0.00 80.00 0.00 0.00 80.00 7 >>> kswapd0 >>> 08:36:55 0 93 0.00 64.00 0.00 0.00 64.00 7 >>> kswapd0 >>> 08:36:56 0 93 0.00 56.00 0.00 0.00 56.00 7 >>> kswapd0 >>> 08:36:57 0 93 0.00 26.00 0.00 0.00 26.00 2 >>> kswapd0 >>> 08:36:58 0 93 0.00 24.00 0.00 1.00 24.00 3 >>> kswapd0 >>> 08:36:59 0 93 0.00 22.00 0.00 1.00 22.00 3 >>> kswapd0 >>> 08:37:00 0 93 0.00 15.84 0.00 0.00 15.84 3 >>> kswapd0 >>> 08:37:01 0 93 0.00 0.00 0.00 0.00 0.00 3 >>> kswapd0 >>> 08:37:02 0 93 0.00 0.00 0.00 0.00 0.00 3 >>> kswapd0 >>> >>> Read test data after using uncached buffer I/O: >>> reading bs 32768, uncached 1 >>> 1s: 1863MB/sec, MB=1863 >>> 2s: 1903MB/sec, MB=3766 >>> 3s: 1860MB/sec, MB=5627 >>> 4s: 1864MB/sec, MB=7491 >>> 5s: 1860MB/sec, MB=9352 >>> 6s: 1854MB/sec, MB=11206 >>> 7s: 1874MB/sec, MB=13081 >>> 8s: 1874MB/sec, MB=14943 >>> 9s: 1840MB/sec, MB=16798 >>> 10s: 1849MB/sec, MB=18647 >>> 11s: 1863MB/sec, MB=20511 >>> 12s: 1798MB/sec, MB=22310 >>> 13s: 1897MB/sec, MB=24207 >>> 14s: 1817MB/sec, MB=26025 >>> 15s: 1893MB/sec, MB=27918 >>> 16s: 1917MB/sec, MB=29836 >>> 17s: 1863MB/sec, MB=31699 >>> 18s: 1904MB/sec, MB=33604 >>> 19s: 1894MB/sec, MB=35499 >>> 20s: 1907MB/sec, MB=37407 >>> >>> 08:38:00 UID PID %usr %system %guest %wait %CPU CPU >>> Command >>> 08:38:01 0 93 0.00 0.00 0.00 0.00 0.00 4 >>> kswapd0 >>> 08:38:02 0 93 0.00 0.00 0.00 0.00 0.00 4 >>> kswapd0 >>> 08:38:03 0 93 0.00 0.00 0.00 0.00 0.00 4 >>> kswapd0 >>> 08:38:04 0 93 0.00 0.00 0.00 0.00 0.00 4 >>> kswapd0 >>> 08:38:05 0 93 0.00 0.00 0.00 0.00 0.00 4 >>> kswapd0 >>> 08:38:06 0 93 0.00 1.00 0.00 1.00 1.00 0 >>> kswapd0 >>> 08:38:07 0 93 0.00 0.00 0.00 0.00 0.00 0 >>> kswapd0 >>> 08:38:08 0 93 0.00 0.00 0.00 0.00 0.00 0 >>> kswapd0 >>> 08:38:09 0 93 0.00 1.00 0.00 0.00 1.00 1 >>> kswapd0 >>> 08:38:10 0 93 0.00 0.00 0.00 0.00 0.00 1 >>> kswapd0 >>> 08:38:11 0 93 0.00 0.00 0.00 0.00 0.00 1 >>> kswapd0 >>> 08:38:12 0 93 0.00 0.00 0.00 0.00 0.00 1 >>> kswapd0 >>> 08:38:13 0 93 0.00 0.00 0.00 0.00 0.00 1 >>> kswapd0 >>> 08:38:14 0 93 0.00 0.00 0.00 0.00 0.00 1 >>> kswapd0 >>> 08:38:15 0 93 0.00 3.00 0.00 0.00 3.00 0 >>> kswapd0 >>> 08:38:16 0 93 0.00 0.00 0.00 0.00 0.00 0 >>> kswapd0 >>> 08:38:17 0 93 0.00 0.00 0.00 0.00 0.00 0 >>> kswapd0 >>> 08:38:18 0 93 0.00 0.00 0.00 0.00 0.00 0 >>> kswapd0 >>> 08:38:19 0 93 0.00 0.00 0.00 0.00 0.00 0 >>> kswapd0 >>> 08:38:20 0 93 0.00 0.00 0.00 0.00 0.00 0 >>> kswapd0 >>> 08:38:21 0 93 0.00 0.00 0.00 0.00 0.00 0 >>> kswapd0 >>> 08:38:22 0 93 0.00 0.00 0.00 0.00 0.00 0 >>> kswapd0 >>> 08:38:23 0 93 0.00 3.00 0.00 0.00 3.00 4 >>> kswapd0 >>> 08:38:24 0 93 0.00 0.00 0.00 0.00 0.00 4 >>> kswapd0 >>> 08:38:25 0 93 0.00 0.00 0.00 0.00 0.00 4 >>> kswapd0 >>> 08:38:26 0 93 0.00 4.00 0.00 0.00 4.00 3 >>> kswapd0 >>> 08:38:27 0 93 0.00 0.00 0.00 0.00 0.00 3 >>> kswapd0 >>> 08:38:28 0 93 0.00 0.00 0.00 0.00 0.00 3 >>> kswapd0 >>> 08:38:29 0 93 0.00 0.00 0.00 0.00 0.00 3 >>> kswapd0 >>> 08:38:30 0 93 0.00 0.00 0.00 0.00 0.00 3 >>> kswapd0 >>> 08:38:31 0 93 0.00 0.00 0.00 0.00 0.00 3 >>> kswapd0 >>> 08:38:32 0 93 0.00 0.00 0.00 0.00 0.00 3 >>> kswapd0 >>> 08:38:33 0 93 0.00 0.00 0.00 0.00 0.00 3 >>> kswapd0 >>> >>> [1] >>> https://lore.kernel.org/all/20241220154831.1086649-10-ax...@kernel.dk/T/#m58520a94b46f543d82db3711453dfc7bb594b2b0 >>> >>> [2] >>> https://pastebin.com/u8eCBzB5 >>> >>> Signed-off-by: Qi Han <ha...@vivo.com> >>> --- >>> fs/f2fs/file.c | 2 +- >>> 1 file changed, 1 insertion(+), 1 deletion(-) >>> >>> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c >>> index 696131e655ed..d8da1fc2febf 100644 >>> --- a/fs/f2fs/file.c >>> +++ b/fs/f2fs/file.c >>> @@ -5425,5 +5425,5 @@ const struct file_operations f2fs_file_operations = { >>> .splice_read = f2fs_file_splice_read, >>> .splice_write = iter_file_splice_write, >>> .fadvise = f2fs_file_fadvise, >>> - .fop_flags = FOP_BUFFER_RASYNC, >>> + .fop_flags = FOP_BUFFER_RASYNC | FOP_DONTCACHE, >>> }; > _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
