On 2018-01-08 14:38:20 +1300, Thomas Munro wrote:
> Just an idea, not sure if it's worth looking into; maybe we already
> spend enough time filling those buffers that a 50% syscall markup
> won't hurt.
Yea, I suspect that won't make a huge difference - copying an 8kb buffer
is typically a lot more
On Mon, Jan 8, 2018 at 1:32 PM, Thomas Munro
wrote:
> Also pgarch.c, syncrep.c, walsender.c and walreceiver.c use
> PostmasterIsAlive() every time through their loops[1] generating extra
> syscalls, one instance of which has caused complaints before[1] on a
> system where the syscall was expensive
On Mon, Jan 8, 2018 at 2:38 PM, Thomas Munro
wrote:
> On Fri, Jan 5, 2018 at 6:28 AM, Robert Haas wrote:
>> On Tue, Jan 2, 2018 at 5:23 PM, Andres Freund wrote:
>>> Note that real-world scenarios probably will see somewhat smaller
>>> impact, as this was measured over a loopback unix sockets whi
On Fri, Jan 5, 2018 at 6:28 AM, Robert Haas wrote:
> On Tue, Jan 2, 2018 at 5:23 PM, Andres Freund wrote:
>> Note that real-world scenarios probably will see somewhat smaller
>> impact, as this was measured over a loopback unix sockets which'll have
>> smaller overhead itself than proper TCP sock
On Tue, Jan 2, 2018 at 5:23 PM, Andres Freund wrote:
> To get closer to the worst case, I've also measured:
>
> pgbench SELECT 1, 16 clients, i7-6820HQ CPU (skylake):
>
> pti=off:
> tps = 420490.162391
>
> pti=on:
> tps = 350746.065039 (~0.83x)
>
> pti=on, nopcid:
> tps = 324269.903152 (~0.77x)
>
