Re: [Qemu-devel] [PATCH COLO-Frame v10 17/38] COLO: synchronize PVM's state to SVM periodically

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* zhanghailiang (zhang.zhanghailiang@huawei.com) wrote:
> On 2015/11/14 2:34, Dr. David Alan Gilbert wrote:
> >* zhanghailiang (zhang.zhanghailiang@huawei.com) wrote:
> >>Do checkpoint periodically, the default interval is 200ms.
> >>
> >>Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
> >>Signed-off-by: Li Zhijian <lizhijian@cn.fujitsu.com>
> >>---
> >>  migration/colo.c | 14 ++++++++++++++
> >>  1 file changed, 14 insertions(+)
> >>
> >>diff --git a/migration/colo.c b/migration/colo.c
> >>index 0efab21..a6791f4 100644
> >>--- a/migration/colo.c
> >>+++ b/migration/colo.c
> >>@@ -11,12 +11,19 @@
> >>   */
> >>
> >>  #include <unistd.h>
> >>+#include "qemu/timer.h"
> >>  #include "sysemu/sysemu.h"
> >>  #include "migration/colo.h"
> >>  #include "trace.h"
> >>  #include "qemu/error-report.h"
> >>  #include "qemu/sockets.h"
> >>
> >>+/*
> >>+ * checkpoint interval: unit ms
> >>+ * Note: Please change this default value to 10000 when we support hybrid mode.
> >>+ */
> >>+#define CHECKPOINT_MAX_PEROID 200
> >
> >Why not put the patch that makes this a configurable parameter before this,
> >and then we can use it straight away?
> >
> 
> Do you mean setting this value by command  "migrate_set_parameter" ?
> I have realized it in patch 26.

Yes, I mean reorder the patch series; put the migrate_set_parameter addition
before this patch, and then use it straight away.

Dave

> >>  /* colo buffer */
> >>  #define COLO_BUFFER_BASE_SIZE (4 * 1024 * 1024)
> >>
> >>@@ -183,6 +190,7 @@ out:
> >>  static void colo_process_checkpoint(MigrationState *s)
> >>  {
> >>      QEMUSizedBuffer *buffer = NULL;
> >>+    int64_t current_time, checkpoint_time = qemu_clock_get_ms(QEMU_CLOCK_HOST);
> >>      int fd, ret = 0;
> >>
> >>      /* Dup the fd of to_dst_file */
> >>@@ -220,11 +228,17 @@ static void colo_process_checkpoint(MigrationState *s)
> >>      trace_colo_vm_state_change("stop", "run");
> >>
> >>      while (s->state == MIGRATION_STATUS_COLO) {
> >>+        current_time = qemu_clock_get_ms(QEMU_CLOCK_HOST);
> >>+        if (current_time - checkpoint_time < CHECKPOINT_MAX_PEROID) {
> >>+            g_usleep(100000);
> >>+            continue;
> >>+        }
> >
> >I'm a bit concerned at the 100ms wait, when the period is 200ms;
> >depending how the times work out, couldn't we end up waiting for just
> >under 300ms? - that's a big error - and it's even more weird when
> >we make it configurable later.
> >
> 
> Agreed.
> 
> >I don't think we've got a sleep-until, which is a shame; but how
> >about something like:
> >
> >    if (current_time - checkpoint_time < CHECKPOINT_MAX_PEROID) {
> >        int64_t delay_ms;
> >        delay_ms = CHECKPOINT_MAX_PERIOD - (current_time - checkpoint_time);
> >        g_usleep (delay_ms * 1000);
> >    }
> >
> 
> That's a reasonable modification. I will fix it like that in next version.
> 
> Thanks，
> zhanghailiang
> 
> >Dave
> >
> >>          /* start a colo checkpoint */
> >>          ret = colo_do_checkpoint_transaction(s, buffer);
> >>          if (ret < 0) {
> >>              goto out;
> >>          }
> >>+        checkpoint_time = qemu_clock_get_ms(QEMU_CLOCK_HOST);
> >>      }
> >>
> >>  out:
> >>--
> >>1.8.3.1
> >>
> >>
> >--
> >Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
> >
> >.
> >
> 
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK