Re: x86-64 and PostgreSQL
От | Shridhar Daithankar |
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Тема | Re: x86-64 and PostgreSQL |
Дата | |
Msg-id | 3E2C15E6.9191.DF2FEFC@localhost обсуждение исходный текст |
Ответ на | Re: x86-64 and PostgreSQL (Ron Johnson <ron.l.johnson@cox.net>) |
Ответы |
Re: x86-64 and PostgreSQL
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Список | pgsql-performance |
On 20 Jan 2003 at 3:52, Ron Johnson wrote: > On Mon, 2003-01-20 at 00:29, Shridhar Daithankar wrote: > > I remember reading in one of the HP guides regarding 64 bit that 64 bit is a > > tool provided for applications. In general no app. should be 64 bit unless > > required. In fact they advice that fastest performance one can get is by > > running 32 bit app. on 64 bit machine because registers are wide and can be > > filled in is less number of fetches. > > > > Sounds reasonable to me. > > Dou you, the programmer or SysAdmin, always know when 64 bits is > needed? > > Take, for simple example, a memcpy() of 1024 bytes. Most CPUs don't > have direct core-core copy instruction. (The RISC philosophy, after > all, is load-and-store.) A 32-bit executable would need 1024/32 = 32 > pairs of load-store operations, while a 64-bit executable would only > need 16. Yes, L1 & L2 caching would help some, but not if you are > moving huge amounts of data... Well, that wasn't intended application aera of that remark. I was more on the line of, I have 16GB data of double precision which I need to shuffle thr. once in a while, should I use 32 bit or 64 bit? Something like that.. bit more macroscopic. I work on an application which is 32 bit on HP-UX 64 bit. It handles more than 15GB of data at some sites pretty gracefully..No need to move to 64 bit as yet.. Bye Shridhar -- Kramer's Law: You can never tell which way the train went by looking at the tracks.
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