Re: [Monotone-devel] [PATCH] pre-cache database file to improve response time

[Joe Wilson]

--- Ulrich Drepper <address@hidden> wrote:
> Joe Wilson wrote:
> > Here's a patch to improve the speed of many database-intensive monotone 
> > commands.
> > 
> > It can shave 70% of the time off of a (cold) checkout, for example.
> 
> It might, but it does so violently.  It's forcing other data out of the
> caches.

Certainly much less violently than having a big monotone operation 
randomly hit the disk for several extra minutes.
Admittedly, it's crude, but it will work on most operating systems 
(including Windows). If a faster, more portable and more elegant
way can be found, then it should be used. Until then, there's no
harm in using this simple and easy to revert patch.

> Modern OSes have support for hints to the OS.  For mmap() calls on
> Linux, there is the MAP_POPULATE flag.  For all file operations, there
> is posix_fadvise().

SQLite does not use mmap() - just basic read()s and write()s for
portability. Can the system calls you mention be made to work
with Monotone without altering SQLite's library code?
(Does Windows natively support mmap()?)

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