Re: [PATCH v8 0/6] block: seriously improve savevm/loadvm performance
On Thu, Jul 09, 2020 at 04:26:38PM +0300, Denis V. Lunev wrote: > This series do standard basic things: > - it creates intermediate buffer for all writes from QEMU migration code > to QCOW2 image, > - this buffer is sent to disk asynchronously, allowing several writes to > run in parallel. > > In general, migration code is fantastically inefficent (by observation), > buffers are not aligned and sent with arbitrary pieces, a lot of time > less than 100 bytes at a chunk, which results in read-modify-write > operations with non-cached operations. It should also be noted that all > operations are performed into unallocated image blocks, which also suffer > due to partial writes to such new clusters. > > This patch series is an implementation of idea discussed in the RFC > posted by Denis Plotnikov > https://lists.gnu.org/archive/html/qemu-devel/2020-04/msg01925.html > Results with this series over NVME are better than original code > original rfcthis > cached: 1.79s 2.38s 1.27s > non-cached: 3.29s 1.31s 0.81s Kevin and Max: Is this going through one of your trees? Stefan signature.asc Description: PGP signature
Re: [PATCH v8 0/6] block: seriously improve savevm/loadvm performance
On 8/20/20 10:42 AM, Denis V. Lunev wrote: > On 7/9/20 4:26 PM, Denis V. Lunev wrote: >> This series do standard basic things: >> - it creates intermediate buffer for all writes from QEMU migration code >> to QCOW2 image, >> - this buffer is sent to disk asynchronously, allowing several writes to >> run in parallel. >> >> In general, migration code is fantastically inefficent (by observation), >> buffers are not aligned and sent with arbitrary pieces, a lot of time >> less than 100 bytes at a chunk, which results in read-modify-write >> operations with non-cached operations. It should also be noted that all >> operations are performed into unallocated image blocks, which also suffer >> due to partial writes to such new clusters. >> >> This patch series is an implementation of idea discussed in the RFC >> posted by Denis Plotnikov >> https://lists.gnu.org/archive/html/qemu-devel/2020-04/msg01925.html >> Results with this series over NVME are better than original code >> original rfcthis >> cached: 1.79s 2.38s 1.27s >> non-cached: 3.29s 1.31s 0.81s >> >> Changes from v7: >> - dropped lock from LoadVMState >> - fixed assert in last patch >> - dropped patch 1 as queued >> >> Changes from v6: >> - blk_load_vmstate kludges added (patchew problem fixed) >> >> Changes from v5: >> - loadvm optimizations added with Vladimir comments included >> >> Changes from v4: >> - added patch 4 with blk_save_vmstate() cleanup >> - added R-By >> - bdrv_flush_vmstate -> bdrv_finalize_vmstate >> - fixed return code of bdrv_co_do_save_vmstate >> - fixed typos in comments (Eric, thanks!) >> - fixed patchew warnings >> >> Changes from v3: >> - rebased to master >> - added patch 3 which removes aio_task_pool_wait_one() >> - added R-By to patch 1 >> - patch 4 is rewritten via bdrv_run_co >> - error path in blk_save_vmstate() is rewritten to call bdrv_flush_vmstate >> unconditionally >> - added some comments >> - fixes initialization in bdrv_co_vmstate_save_task_entry as suggested >> >> Changes from v2: >> - code moved from QCOW2 level to generic block level >> - created bdrv_flush_vmstate helper to fix 022, 029 tests >> - added recursive for bs->file in bdrv_co_flush_vmstate (fix 267) >> - fixed blk_save_vmstate helper >> - fixed coroutine wait as Vladimir suggested with waiting fixes from me >> >> Changes from v1: >> - patchew warning fixed >> - fixed validation that only 1 waiter is allowed in patch 1 >> >> Signed-off-by: Denis V. Lunev >> CC: Kevin Wolf >> CC: Max Reitz >> CC: Stefan Hajnoczi >> CC: Fam Zheng >> CC: Juan Quintela >> CC: "Dr. David Alan Gilbert" >> CC: Vladimir Sementsov-Ogievskiy >> CC: Denis Plotnikov >> >> > ping ping V2
Re: [PATCH v8 0/6] block: seriously improve savevm/loadvm performance
On 7/9/20 4:26 PM, Denis V. Lunev wrote: > This series do standard basic things: > - it creates intermediate buffer for all writes from QEMU migration code > to QCOW2 image, > - this buffer is sent to disk asynchronously, allowing several writes to > run in parallel. > > In general, migration code is fantastically inefficent (by observation), > buffers are not aligned and sent with arbitrary pieces, a lot of time > less than 100 bytes at a chunk, which results in read-modify-write > operations with non-cached operations. It should also be noted that all > operations are performed into unallocated image blocks, which also suffer > due to partial writes to such new clusters. > > This patch series is an implementation of idea discussed in the RFC > posted by Denis Plotnikov > https://lists.gnu.org/archive/html/qemu-devel/2020-04/msg01925.html > Results with this series over NVME are better than original code > original rfcthis > cached: 1.79s 2.38s 1.27s > non-cached: 3.29s 1.31s 0.81s > > Changes from v7: > - dropped lock from LoadVMState > - fixed assert in last patch > - dropped patch 1 as queued > > Changes from v6: > - blk_load_vmstate kludges added (patchew problem fixed) > > Changes from v5: > - loadvm optimizations added with Vladimir comments included > > Changes from v4: > - added patch 4 with blk_save_vmstate() cleanup > - added R-By > - bdrv_flush_vmstate -> bdrv_finalize_vmstate > - fixed return code of bdrv_co_do_save_vmstate > - fixed typos in comments (Eric, thanks!) > - fixed patchew warnings > > Changes from v3: > - rebased to master > - added patch 3 which removes aio_task_pool_wait_one() > - added R-By to patch 1 > - patch 4 is rewritten via bdrv_run_co > - error path in blk_save_vmstate() is rewritten to call bdrv_flush_vmstate > unconditionally > - added some comments > - fixes initialization in bdrv_co_vmstate_save_task_entry as suggested > > Changes from v2: > - code moved from QCOW2 level to generic block level > - created bdrv_flush_vmstate helper to fix 022, 029 tests > - added recursive for bs->file in bdrv_co_flush_vmstate (fix 267) > - fixed blk_save_vmstate helper > - fixed coroutine wait as Vladimir suggested with waiting fixes from me > > Changes from v1: > - patchew warning fixed > - fixed validation that only 1 waiter is allowed in patch 1 > > Signed-off-by: Denis V. Lunev > CC: Kevin Wolf > CC: Max Reitz > CC: Stefan Hajnoczi > CC: Fam Zheng > CC: Juan Quintela > CC: "Dr. David Alan Gilbert" > CC: Vladimir Sementsov-Ogievskiy > CC: Denis Plotnikov > > ping
[PATCH v8 0/6] block: seriously improve savevm/loadvm performance
This series do standard basic things: - it creates intermediate buffer for all writes from QEMU migration code to QCOW2 image, - this buffer is sent to disk asynchronously, allowing several writes to run in parallel. In general, migration code is fantastically inefficent (by observation), buffers are not aligned and sent with arbitrary pieces, a lot of time less than 100 bytes at a chunk, which results in read-modify-write operations with non-cached operations. It should also be noted that all operations are performed into unallocated image blocks, which also suffer due to partial writes to such new clusters. This patch series is an implementation of idea discussed in the RFC posted by Denis Plotnikov https://lists.gnu.org/archive/html/qemu-devel/2020-04/msg01925.html Results with this series over NVME are better than original code original rfcthis cached: 1.79s 2.38s 1.27s non-cached: 3.29s 1.31s 0.81s Changes from v7: - dropped lock from LoadVMState - fixed assert in last patch - dropped patch 1 as queued Changes from v6: - blk_load_vmstate kludges added (patchew problem fixed) Changes from v5: - loadvm optimizations added with Vladimir comments included Changes from v4: - added patch 4 with blk_save_vmstate() cleanup - added R-By - bdrv_flush_vmstate -> bdrv_finalize_vmstate - fixed return code of bdrv_co_do_save_vmstate - fixed typos in comments (Eric, thanks!) - fixed patchew warnings Changes from v3: - rebased to master - added patch 3 which removes aio_task_pool_wait_one() - added R-By to patch 1 - patch 4 is rewritten via bdrv_run_co - error path in blk_save_vmstate() is rewritten to call bdrv_flush_vmstate unconditionally - added some comments - fixes initialization in bdrv_co_vmstate_save_task_entry as suggested Changes from v2: - code moved from QCOW2 level to generic block level - created bdrv_flush_vmstate helper to fix 022, 029 tests - added recursive for bs->file in bdrv_co_flush_vmstate (fix 267) - fixed blk_save_vmstate helper - fixed coroutine wait as Vladimir suggested with waiting fixes from me Changes from v1: - patchew warning fixed - fixed validation that only 1 waiter is allowed in patch 1 Signed-off-by: Denis V. Lunev CC: Kevin Wolf CC: Max Reitz CC: Stefan Hajnoczi CC: Fam Zheng CC: Juan Quintela CC: "Dr. David Alan Gilbert" CC: Vladimir Sementsov-Ogievskiy CC: Denis Plotnikov
