Fabiano, On Thu, Feb 29, 2024 at 12:29:54PM -0300, Fabiano Rosas wrote: > => guest: 128 GB RAM - 120 GB dirty - 1 vcpu in tight loop dirtying memory
I'm curious normally how much time does it take to do the final fdatasync() for you when you did this test. I finally got a relatively large system today and gave it a quick shot over 128G (100G busy dirty) mapped-ram snapshot with 8 multifd channels. The migration save/load does all fine, so I don't think there's anything wrong with the patchset, however when save completes (I'll need to stop the workload as my disk isn't fast enough I guess..) I'll always hit a super long hang of QEMU on fdatasync() on XFS during which the main thread is in UNINTERRUPTIBLE state. [<0>] rq_qos_wait+0xbb/0x130 [<0>] wbt_wait+0x9c/0x100 [<0>] __rq_qos_throttle+0x23/0x40 [<0>] blk_mq_submit_bio+0x183/0x580 [<0>] __submit_bio_noacct+0x7e/0x1e0 [<0>] iomap_submit_ioend+0x4e/0x80 [<0>] iomap_writepage_map+0x22a/0x400 [<0>] write_cache_pages+0x17c/0x4c0 [<0>] iomap_writepages+0x1c/0x40 [<0>] xfs_vm_writepages+0x7a/0xb0 [xfs] [<0>] do_writepages+0xcf/0x1d0 [<0>] filemap_fdatawrite_wbc+0x66/0x90 [<0>] __filemap_fdatawrite_range+0x54/0x80 [<0>] file_write_and_wait_range+0x48/0xb0 [<0>] xfs_file_fsync+0x5a/0x240 [xfs] [<0>] __x64_sys_fdatasync+0x46/0x80 [<0>] do_syscall_64+0x5c/0x90 [<0>] entry_SYSCALL_64_after_hwframe+0x72/0xdc Do you also have it, or it's just my host kernel / other config that is different? -- Peter Xu