On Tuesday, January 24, 2023 3:38:23 AM CET Eric Van Hensbergen wrote: > This is the third version of a patch series which adds a number > of features to improve read/write performance in the 9p filesystem. > Mostly it focuses on fixing caching to help utilize the recently > increased MSIZE limits and also fixes some problematic behavior > within the writeback code. > > All together, these show roughly 10x speed increases on simple > file transfers. Future patch sets will improve cache consistency > and directory caching. > > These patches are also available on github: > https://github.com/v9fs/linux/tree/ericvh/for-next > and on kernel.org: > https://git.kernel.org/pub/scm/linux/kernel/git/ericvh/v9fs.git > > Tested against qemu, cpu, and diod with fsx, dbench, and some > simple benchmarks. Looks like this needs more work. I only had a glimpse on your patches yet, but made some tests by doing compilations on guest on top of a 9p root fs [1], msize=500k. Under that scenario: * loose: this is suprisingly the only mode where I can see some performance increase, over "loose" on master it compiled ~5% faster, but I also got some misbehaviours on guest. * writeahead: no performance results, as compilation already aborts when trying to detect a compiler. I had to restore a previous snapshot to repair things after this test. * readahead: significant performance drop. In comparison to "loose" on master compilation takes 6 times longer with "readahead". There are some severe misbehaviours on guest as well, and after boot I get this warning: [ 5.782846] folio expected an open fid inode->i_private=0000000000000000 [ 5.786641] WARNING: CPU: 0 PID: 321 at fs/9p/vfs_addr.c:174 v9fs_vfs_write_folio_locked (fs/9p/vfs_addr.c:174 (discriminator 3)) 9p [ 5.792496] Modules linked in: ppdev(E) bochs(E) sg(E) drm_vram_helper(E) joydev(E) evdev(E) drm_kms_helper(E) serio_raw(E) drm_ttm_helper(E) pcsp) [ 5.816806] CPU: 0 PID: 321 Comm: chown Tainted: G E 6.2.0-rc6+ #61 [ 5.821694] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.1-0-g3208b098f51a-prebuilt.qemu.org 04/01/2014 [ 5.827362] RIP: 0010:v9fs_vfs_write_folio_locked (fs/9p/vfs_addr.c:174 (discriminator 3)) 9p Code starting with the faulting instruction =========================================== ... [ 5.835360] RSP: 0018:ffffc900007d3a38 EFLAGS: 00010282 [ 5.836982] RAX: 0000000000000000 RBX: ffff888106c86680 RCX: 0000000000000000 [ 5.838877] RDX: 0000000000000001 RSI: ffffffff821eb1e6 RDI: 00000000ffffffff [ 5.841179] RBP: ffffea0004279300 R08: 0000000000000000 R09: 00000000ffffefff [ 5.843039] R10: ffffc900007d38e8 R11: ffffffff824bede8 R12: 0000000000000000 [ 5.844850] R13: 00000000ffffffea R14: 0000000000000014 R15: 0000000000000014 [ 5.846366] FS: 00007fd0fc4a0580(0000) GS:ffff88842fc00000(0000) knlGS:0000000000000000 [ 5.848250] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 5.849386] CR2: 00007fd0fc38f4f0 CR3: 0000000100302000 CR4: 00000000000006f0 [ 5.850824] Call Trace: [ 5.851622] <TASK> [ 5.852052] v9fs_vfs_writepage (fs/9p/vfs_addr.c:207) 9p [ 5.852841] __writepage (mm/page-writeback.c:2537) [ 5.853438] write_cache_pages (mm/page-writeback.c:2473) [ 5.854205] ? __pfx___writepage (mm/page-writeback.c:2535) [ 5.855309] ? delete_node (lib/radix-tree.c:575) [ 5.856122] ? radix_tree_delete_item (lib/radix-tree.c:1432) [ 5.857101] do_writepages (mm/page-writeback.c:2564 mm/page-writeback.c:2552 mm/page-writeback.c:2583) [ 5.857954] ? radix_tree_delete_item (lib/radix-tree.c:1432) [ 5.859103] filemap_fdatawrite_wbc (mm/filemap.c:389 mm/filemap.c:378) [ 5.860043] __filemap_fdatawrite_range (mm/filemap.c:422) [ 5.861050] filemap_write_and_wait_range (mm/filemap.c:682 mm/filemap.c:665) [ 5.862132] v9fs_vfs_setattr_dotl (./include/linux/pagemap.h:60 fs/9p/vfs_inode_dotl.c:583) 9p [ 5.863312] notify_change (fs/attr.c:486) [ 5.864043] ? chown_common (fs/open.c:736) [ 5.864793] chown_common (fs/open.c:736) [ 5.865538] ? preempt_count_add (./include/linux/ftrace.h:977 kernel/sched/core.c:5737 kernel/sched/core.c:5734 kernel/sched/core.c:5762) [ 5.866420] do_fchownat (fs/open.c:768) [ 5.867419] __x64_sys_fchownat (fs/open.c:782 fs/open.c:779 fs/open.c:779) [ 5.868319] do_syscall_64 (arch/x86/entry/common.c:50 arch/x86/entry/common.c:80) [ 5.869116] entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:120) [ 5.871008] RIP: 0033:0x7fd0fc3b7b9a Best regards, Christian Schoenebeck [1] https://wiki.qemu.org/Documentation/9p_root_fs
