| From: | David Geier <geidav(dot)pg(at)gmail(dot)com> |
|---|---|
| To: | Andres Freund <andres(at)anarazel(dot)de> |
| Cc: | Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>, Tomas Vondra <tomas(dot)vondra(at)enterprisedb(dot)com>, vignesh C <vignesh21(at)gmail(dot)com>, Lukas Fittl <lukas(at)fittl(dot)com>, Michael Paquier <michael(at)paquier(dot)xyz>, Ibrar Ahmed <ibrar(dot)ahmad(at)gmail(dot)com>, Maciek Sakrejda <m(dot)sakrejda(at)gmail(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Reduce timing overhead of EXPLAIN ANALYZE using rdtsc? |
| Date: | 2023-02-14 11:11:01 |
| Message-ID: | 989acbcf-e950-7911-c2e2-fe7aa7d15108@gmail.com |
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| Thread: | |
| Lists: | pgsql-hackers |
Hi,
On 2/7/23 19:12, Andres Freund wrote:
> This fails to build on several platforms:
>
> https://cirrus-ci.com/github/postgresql-cfbot/postgresql/commitfest%2F42%2F3751
I think I fixed the compilation errors. It was due to a few variables
being declared under
#if defined(__x86_64__) && defined(__linux__)
while being used also under non x86 Linux.
I also removed again the code to obtain the TSC frequency under
hypervisors because the TSC is usually emulated and therefore no faster
than clock_gettime() anyways. So we now simply fallback to
clock_gettime() on hypervisors when we cannot obtain the frequency via
leaf 0x16.
Beyond that I reviewed the first two patches a while ago in [1]. I hope
we can progress with them to further reduce the size of this patch set.
[1]
https://www.postgresql.org/message-id/3ac157f7-085d-e071-45fc-b87cd306360c%40gmail.com
--
David Geier
(ServiceNow)
| Attachment | Content-Type | Size |
|---|---|---|
| v8-0001-instr_time-Add-INSTR_TIME_SET_SECONDS-INSTR_TIME_.patch | text/x-patch | 2.0 KB |
| v8-0002-wip-report-nanoseconds-in-pg_test_timing.patch | text/x-patch | 11.3 KB |
| v8-0003-Use-RDTSC-P-instructions-to-measure-time-on-x86-L.patch | text/x-patch | 17.4 KB |
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