On Fri, Apr 05, 2024 at 07:36:42AM -0400, Mouse wrote:
>
> Well, I'm not the one (putatively) doing the work. But my answers to
> that are:
>
Me neither.
> (1) Small sorts are not the issue, IMO. Even a speedup as great as
> halving the time taken is not enough to worry about when it's on a p
>> (4) Are there still incoherencies between mmap and read/write
>> access? At one time there were, [...]
> This bug was fixed nearly a quarter century ago, in November 2000,
> with the merge of the unified buffer cache.
Ah, I recall UBC being brought in.
> I think using any version of NetBSD re
> Date: Fri, 5 Apr 2024 07:36:42 -0400 (EDT)
> From: Mouse
>
> (4) Are there still incoherencies between mmap and read/write access?
> At one time there were, and I never got a good handle on what needed to
> be done to avoid them.
This bug was fixed nearly a quarter century ago, in November 200
>> [...]
> Why not stat the input file and decide to use in memory iff the file
> is small enough? This way sort will handle large sorts on small
> memory machines automatically.
Well, I'm not the one (putatively) doing the work. But my answers to
that are:
(1) Small sorts are not the issue, IM
On Thu, Apr 04, 2024 at 02:38:02PM +0200, Martin Husemann wrote:
>
> Since the original comment hints at "instead of temp files" it is pretty
> clear that the second variant is meant. This avoids all file system operations
> and if the machine you run on has enough free memory it might not even
>
On Thursday, April 4, 2024 11:28:13 PM CEST Robert Elz wrote:
> Yes, in cases where temp files are actually needed, using mmap() is a
> very minor gain indeed - the buffering cost might be saved, but sorting
> a large file is a cpu costly endeavour (lots of comparisons, lots of times
> even with th
Date:Thu, 4 Apr 2024 10:05:17 -0400 (EDT)
From:Mouse
Message-ID: <202404041405.kaa01...@stone.rodents-montreal.org>
| Actually, if you mmap it PROT_WRITE and MAP_PRIVATE, you could go right
| ahead. But that'll cost RAM or swap space when the COW fault happens.
>> Given the issues about using mmap, can anybody suggest how I should
>> proceed with the implementation, or if I should at all?
> There are two potential ways where mmap(2) could help improve the speed
> of sort:
> - If you know the input file name, use a read-only mmap() of that file
>and
On Thu, Apr 04, 2024 at 12:02:30PM +, Ice Cream wrote:
> Given the issues about using mmap, can anybody suggest how
> I should proceed with the implementation, or if I should at all?
There are two potential ways where mmap(2) could help improve the speed
of sort:
- If you know the input file
