debian/patches/pve/0047-savevm-async-flush-IOThread-drives-async-before-ente.patch

   1 From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
   2 From: Stefan Reiter <s.reiter@proxmox.com>
   3 Date: Wed, 27 May 2020 11:33:21 +0200
   4 Subject: [PATCH] savevm-async: flush IOThread-drives async before entering
   5  blocking part
   6
   7 By flushing all drives where its possible to so before entering the
   8 blocking part (where the VM is stopped), we can reduce the time spent in
   9 said part for every disk that has an IOThread (other drives cannot be
  10 flushed async anyway).
  11
  12 Suggested-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
  13 Signed-off-by: Stefan Reiter <s.reiter@proxmox.com>
  14 ---
  15  savevm-async.c | 23 +++++++++++++++++++++++
  16  1 file changed, 23 insertions(+)
  17
  18 diff --git a/savevm-async.c b/savevm-async.c
  19 index 2894c94233..4ce83a0691 100644
  20 --- a/savevm-async.c
  21 +++ b/savevm-async.c
  22 @@ -253,6 +253,8 @@ static void coroutine_fn process_savevm_co(void *opaque)
  23  {
  24      int ret;
  25      int64_t maxlen;
  26 +    BdrvNextIterator it;
  27 +    BlockDriverState *bs = NULL;
  28
  29      ret = qemu_file_get_error(snap_state.file);
  30      if (ret < 0) {
  31 @@ -288,6 +290,27 @@ static void coroutine_fn process_savevm_co(void *opaque)
  32          }
  33      }
  34
  35 +    /* If a drive runs in an IOThread we can flush it async, and only
  36 +     * need to sync-flush whatever IO happens between now and
  37 +     * vm_stop_force_state. bdrv_next can only be called from main AioContext,
  38 +     * so move there now and after every flush.
  39 +     */
  40 +    aio_co_reschedule_self(qemu_get_aio_context());
  41 +    for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
  42 +        /* target has BDRV_O_NO_FLUSH, no sense calling bdrv_flush on it */
  43 +        if (bs == blk_bs(snap_state.target)) {
  44 +            continue;
  45 +        }
  46 +
  47 +        AioContext *bs_ctx = bdrv_get_aio_context(bs);
  48 +        if (bs_ctx != qemu_get_aio_context()) {
  49 +            DPRINTF("savevm: async flushing drive %s\n", bs->filename);
  50 +            aio_co_reschedule_self(bs_ctx);
  51 +            bdrv_flush(bs);
  52 +            aio_co_reschedule_self(qemu_get_aio_context());
  53 +        }
  54 +    }
  55 +
  56      qemu_bh_schedule(snap_state.finalize_bh);
  57  }
  58