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Re: [Qemu-devel] [PATCH V2 1/4] net/colo-compare.c: Add checkpoint min p
From: |
Dr. David Alan Gilbert |
Subject: |
Re: [Qemu-devel] [PATCH V2 1/4] net/colo-compare.c: Add checkpoint min period to optimize performance |
Date: |
Mon, 17 Jul 2017 13:24:23 +0100 |
User-agent: |
Mutt/1.8.3 (2017-05-23) |
* Zhang Chen (address@hidden) wrote:
>
>
> On 07/14/2017 08:10 PM, Dr. David Alan Gilbert wrote:
> > * Zhang Chen (address@hidden) wrote:
> > > If colo-compare find out the first different packet that means
> > > the following packet almost is different. we needn't do a lot
> > > of checkpoint in this time, so we set the no-need-checkpoint
> > > peroid, default just set 3 second.
> > >
> > > Signed-off-by: Zhang Chen <address@hidden>
> > > ---
> > > net/colo-compare.c | 13 ++++++++++++-
> > > 1 file changed, 12 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/net/colo-compare.c b/net/colo-compare.c
> > > index 6d500e1..0f8e198 100644
> > > --- a/net/colo-compare.c
> > > +++ b/net/colo-compare.c
> > > @@ -40,6 +40,9 @@
> > > /* TODO: Should be configurable */
> > > #define REGULAR_PACKET_CHECK_MS 3000
> > > +/* TODO: Should be configurable */
> > Yes it should!
> >
> > > +#define CHECKPOINT_MIN_TIME 3000
> > > +
> > > /*
> > > + CompareState ++
> > > | |
> > > @@ -455,6 +458,7 @@ static void colo_compare_connection(void *opaque,
> > > void *user_data)
> > > Packet *pkt = NULL;
> > > GList *result = NULL;
> > > int ret;
> > > + static int64_t checkpoint_time_ms;
> > > while (!g_queue_is_empty(&conn->primary_list) &&
> > > !g_queue_is_empty(&conn->secondary_list)) {
> > > @@ -494,7 +498,14 @@ static void colo_compare_connection(void *opaque,
> > > void *user_data)
> > > */
> > > trace_colo_compare_main("packet different");
> > > g_queue_push_tail(&conn->primary_list, pkt);
> > > - /* TODO: colo_notify_checkpoint();*/
> > > +
> > > + if (pkt->creation_ms - checkpoint_time_ms >
> > > CHECKPOINT_MIN_TIME) {
> > > + /*
> > > + * TODO: Notify colo frame to do checkpoint.
> > > + * colo_compare_inconsistent_notify();
> > > + */
> > > + checkpoint_time_ms = pkt->creation_ms;
> > > + }
> > You need to be careful how this interacts with the actual start of the
> > checkpoint. Lets say you have two miscompared packets close to each
> > other:
> >
> >
> > miscompare!
> > checkpoint
> > miscompare!
> > ignore it because it was close to the 1st one
> >
> > That means we never trigger the 2nd checkpoint and it'll carry on
> > until the maximum checkpoint length.
> >
> > But also, I think you need to consider what happens to future packets
> > being compared; you can't release any packets now until the checkpoint
> > as soon as you know there's a miscompare.
>
> We need some time to do the checkpoint, and in this period we can ignore
> the miscompare to get better performance. Like that:
>
> currently:
>
> miscompare!
> notify checkpoint
> miscompare!
> notify checkpoint
> miscompare!
> notify checkpoint
> miscompare!
> notify checkpoint
> vm_stop and do checkpoint
>
> vm_start and finish checkpoint
>
> vm_stop and do checkpoint
>
> vm_start and finish checkpoint
>
> vm_stop and do checkpoint
>
> vm_start and finish checkpoint
>
> vm_stop and do checkpoint
>
> vm_start and finish checkpoint
>
>
> running normally.
>
>
> after:
>
> miscompare!
> notify checkpoint
> miscompare!
> ignore
> miscompare!
> ignore
> miscompare!
> ignore
> vm_stop and do checkpoint
>
> vm_start and finish checkpoint
>
> running normally.
Yes, but you must make sure that you don't
ignore any miscompares after the start of the next checkpoint - I don't
see how you avoid that.
Also we must be careful about packets released after the 1st miscompare.
Dave
>
>
> Thanks
> Zhang Chen
>
>
> >
> > Dave
> >
> > > break;
> >
> > > }
> > > }
> > > --
> > > 2.7.4
> > >
> > >
> > >
> > >
> > --
> > Dr. David Alan Gilbert / address@hidden / Manchester, UK
> >
> >
> > .
> >
>
> --
> Thanks
> Zhang Chen
>
>
>
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK
[Qemu-devel] [PATCH V2 3/4] net/colo-compare.c: Optimize unpredictable tcp options comparison, Zhang Chen, 2017/07/13
[Qemu-devel] [PATCH V2 4/4] net/colo-compare.c: Adjust net queue pop order for performance, Zhang Chen, 2017/07/13
[Qemu-devel] [PATCH V2 2/4] net/colo-compare.c: Compare the tcp packets that has the same sequence number, Zhang Chen, 2017/07/13