Re: [HACKERS] lseek/read/write overhead becomes visible at scale ..
От | Tobias Oberstein |
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Тема | Re: [HACKERS] lseek/read/write overhead becomes visible at scale .. |
Дата | |
Msg-id | a7fc2477-d9d6-c695-b40a-76ad341562c9@gmail.com обсуждение исходный текст |
Ответ на | Re: [HACKERS] lseek/read/write overhead becomes visible at scale .. (Andres Freund <andres@anarazel.de>) |
Список | pgsql-hackers |
Hi, >> Synthetic PG workload or real world production workload? > > Both might work, production-like has bigger pull, but I'd guess > synthetic is good enough. Thanks! The box should get PostgreSQL in the not too distant future. It'll get a backup from prod, but will act as new prod, so it might take some time until a job can be run and a profile collected. >> So how would I do a perf profile that would be acceptable as prove? > > You'd have to look at cpu time, not number of syscalls. IIRC I > suggested doing a cycles profile with -g and then using "perf report > --children" to see how many cycles are spent somewhere below lseek. Understood. Either profile manually or expand the function. > I'd also suggest sharing a profile cycles profile, it's quite likely > that the overhead is completely elsewhere. Yeah, could be. It'll be interesting to see for sure. I should get a chance to collect such profile and then I'll post it back here - /Tobias
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