Andres Freund writes:
> On 2018-10-01 20:19:16 -0400, Tom Lane wrote:
>> That patch takes the memset out of the main line, but it'd still be
>> a performance problem for formats using argument reordering; and the
>> stack-space concern would remain the same.
> What I mean is that it shouldn't be
Hi,
On 2018-10-01 17:46:55 -0700, Andres Freund wrote:
> On 2018-10-01 20:19:16 -0400, Tom Lane wrote:
> > argtypes is only a small part of the stack-space issue, there's also
> > argvalues which is (at least) twice as big. I don't think second-guessing
> > the compiler about the most efficient r
Hi,
On 2018-10-01 20:19:16 -0400, Tom Lane wrote:
> Andres Freund writes:
> > On 2018-10-01 19:52:40 -0400, Tom Lane wrote:
> >> Ouch indeed. Quite aside from cycles wasted, that's way more stack than
> >> we want this to consume. I'm good with forcing this to 16 or so ...
> >> any objections?
Thomas Munro writes:
> PrintfArgType is an enum, and we define NL_ARGMAX as 16 if the OS
> didn't already define it. On FreeBSD 11, NL_ARGMAX was defined as 99
> in . On FreeBSD 12, it is defined as 65536... ouch. On a
> Debian box I see it is 4096.
Some further research:
* My Red Hat boxes a
Andres Freund writes:
> On 2018-10-01 19:52:40 -0400, Tom Lane wrote:
>> Ouch indeed. Quite aside from cycles wasted, that's way more stack than
>> we want this to consume. I'm good with forcing this to 16 or so ...
>> any objections?
> Especially after your performance patch, shouldn't we actu
Hi,
On 2018-10-01 19:52:40 -0400, Tom Lane wrote:
> Thomas Munro writes:
> > Mateusz Guzik was benchmarking PostgreSQL on FreeBSD investigating the
> > kqueue thread and complained off-list about a lot of calls to memset()
> > of size 256KB from dopr() in our snprintf.c code.
>
> > Yeah, that sa
Thomas Munro writes:
> Mateusz Guzik was benchmarking PostgreSQL on FreeBSD investigating the
> kqueue thread and complained off-list about a lot of calls to memset()
> of size 256KB from dopr() in our snprintf.c code.
> Yeah, that says:
> PrintfArgType argtypes[NL_ARGMAX + 2];
> ...
> Me
Hello hackers,
Mateusz Guzik was benchmarking PostgreSQL on FreeBSD investigating the
kqueue thread and complained off-list about a lot of calls to memset()
of size 256KB from dopr() in our snprintf.c code.
Yeah, that says:
PrintfArgType argtypes[NL_ARGMAX + 2];
...
MemSet(argtypes, 0, s
