Re: Inlining comparators as a performance optimisation

Поиск
Список
Период
Сортировка
От Heikki Linnakangas
Тема Re: Inlining comparators as a performance optimisation
Дата
Msg-id 4E798974.8030801@enterprisedb.com
обсуждение исходный текст
Ответ на Re: Inlining comparators as a performance optimisation  (Peter Geoghegan <peter@2ndquadrant.com>)
Ответы Re: Inlining comparators as a performance optimisation
Re: Inlining comparators as a performance optimisation
Список pgsql-hackers
On 21.09.2011 02:53, Peter Geoghegan wrote:
> C stdlib quick-sort time elapsed: 2.092451 seconds
> Inline quick-sort time elapsed: 1.587651 seconds
>
> Does *that* look attractive to you?

Not really, to be honest. That's a 25% speedup in pure qsorting speed. 
How much of a gain in a real query do you expect to get from that, in 
the best case? There's so many other sources of overhead that I'm afraid 
this will be lost in the noise. If you find a query that spends, say, 
50% of its time in qsort(), you will only get a 12.5% speedup on that 
query. And even 50% is really pushing it - I challenge you to find a 
query that spends any significant amount of time qsorting integers.

--   Heikki Linnakangas  EnterpriseDB   http://www.enterprisedb.com


В списке pgsql-hackers по дате отправления:

Предыдущее
От: Fujii Masao
Дата:
Сообщение: Re: Online base backup from the hot-standby
Следующее
От: Simon Riggs
Дата:
Сообщение: Re: Inlining comparators as a performance optimisation