Messages in this thread | | | Subject | Re: big picture UDP/IP performance question re 2.6.18 -> 2.6.32 | From | Eric Dumazet <> | Date | Sun, 02 Oct 2011 10:03:23 +0200 |
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Le dimanche 02 octobre 2011 à 09:21 +0200, Eric Dumazet a écrit :
> You might try to disable any fancy power saving mode in your machine. > Maybe on your machine, cost to enter/exit deep sleep state is too high. > > I see nothing obvious in the profile but userland processing, futex > calls.
Just to clarify a bit :
Sometimes, optimizing one part of the kernel can have a negative impact on some workloads because we end up doing more sleep/wakeup of consumers : Several threads might try to acquire a lock at the same time, while previously they got no contention.
In 2.6.35, commit c377411f2494a (net: sk_add_backlog() take rmem_alloc into account) changed backlog limit, avoid taking socket lock on flood, allowing to receive 200.000 pps on a test machine instead of 100pps. But the receiver was doing a plain
while (1) recv(...);
And maximum throughput was reached because task never called scheduler...
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