ase check and (assuming that you agree) run your benchmarks
with the patch applied?
--
Manfred
From fe2f257b1950a19bf5c6f67e71aa25c2f13bcdc3 Mon Sep 17 00:00:00 2001
From: Manfred Spraul
Date: Sun, 24 May 2020 14:47:31 +0200
Subject: [PATCH 2/2] ipc/msg.c: Handle case of senders not enqueuing the
me
gt; > > > @@ -241,6 +242,7 @@ static void ss_wakeup(struct msg_queue *msq,
> > > > > continue;
> > > > > }
> > > > > + msq_quota_used += mss->msgsz;
> > > > > wake_q_ad
he case of a do_msgsnd() that doesn't enqueue the
> > > message:
> > >
> > > Situation:
> > >
> > > - 2 messages of type 1 in the queue (2x8192 bytes, queue full)
> > >
> > > - 6 senders waiting to send messages of type 2
> > >
About your case:
The new receiver puts at the end of the receivers list.
pipelined_send() starts from the beginning of the list and iterates until the
end.
If our queue is always full, each receiver should get a message because new
receivers appends at the end.
In my vision: we waste some time
se of senders not enqueuing the
message
The patch "ipc/msg.c: wake up senders until there is a queue empty
capacity" avoids the thundering herd problem by wakeing up
only as many potential senders as there is free space in the queue.
This patch is a fix: If one of the senders doesn&#x
your patch applied, only one sender sends the message to one receiver,
> and the remaining 10 tasks continue to sleep.
>
>
> Could you please check and (assuming that you agree) run your benchmarks
> with the patch applied?
>
> --
>
> Manfred
>
>
>
>
--
Manfred
>From fe2f257b1950a19bf5c6f67e71aa25c2f13bcdc3 Mon Sep 17 00:00:00 2001
From: Manfred Spraul
Date: Sun, 24 May 2020 14:47:31 +0200
Subject: [PATCH 2/2] ipc/msg.c: Handle case of senders not enqueuing the
message
The patch "ipc/msg.c: wake up senders until there is
Take into account the total size of the already enqueued messages of
previously handled senders before another one.
Otherwise, we have serious degradation of receiver throughput for
case with multiple senders because another sender wakes up,
checks the queue capacity and falls into sleep again.
E
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