From: | Bruce Momjian <maillist(at)candle(dot)pha(dot)pa(dot)us> |
---|---|
To: | goran(at)bildbasen(dot)se (Gran Thyni) |
Cc: | hackers(at)postgreSQL(dot)org, ocie(at)paracel(dot)com |
Subject: | Re: [HACKERS] mmap and MAP_ANON |
Date: | 1998-05-13 15:47:00 |
Message-ID: | 199805131547.LAA15821@candle.pha.pa.us |
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Thread: | |
Lists: | pgsql-hackers |
> *But*,
> (I was thinking about this,)
> we should IMHO take a step backwards to get a better view
> over the whole memory subsystem.
> - Why and for what is shared memory used in the first place?
> - Could we use mmap:ing of files at a higher level then
> src/backend/strorage/ipc/ipc.c to get even better performance
> and cleaness?
Yes, we could use mmap() to map the actual files. I will post time
timings on this soon.
The shared memory acts as a cache for us, that can be locked and not
read in/out of the address space for each sharing, like it does when we
use the OS buffer cache.
>
> I will, time permitting, look into cleaning up the shmem-init/exit
> routines
> to work in a "no-exec" environment. I also has a hack to use
> mmap-shared/private,
> which of course is untested, since it does not work on my linux-boxen.
>
> regards,
> --
> ---------------------------------------------
> Gran Thyni, sysadm, JMS Bildbasen, Kiruna
>
--
Bruce Momjian | 830 Blythe Avenue
maillist(at)candle(dot)pha(dot)pa(dot)us | Drexel Hill, Pennsylvania 19026
+ If your life is a hard drive, | (610) 353-9879(w)
+ Christ can be your backup. | (610) 853-3000(h)
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