Messages in this thread | | | Date | Sat, 26 Nov 2005 11:17:55 +0800 | From | Wu Fengguang <> | Subject | Re: [PATCH 00/19] Adaptive read-ahead V8 |
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On Fri, Nov 25, 2005 at 04:43:17PM +0100, Diego Calleja wrote: > Recently, a openoffice hacker wrote in his blog that the kernel was > culprit of applications not starting as fast as in other systems. > Most of the reasons he gave were wrong, but there was a interesting > one: When you start your system, you've lots of free memory. Since > you have lots of memory, he said it was reasonable to expect that > kernel would readahead *heavily* everything it can to fill that > memory as soon as possible (hoping that what you readahead'ed was > part of the kde/gnome/openoffice libraries etc) and go back to the > normal behaviour when your free memory is used by caches etc. > "Teorically" it looks like a nice heuristic for desktops. Does > adaptative readahead does something like this?
It's interesting ;) In fact some distributions do have a read-ahead script to preload files on startup. The readahead system call should be enough for this purpose:
NAME readahead - perform file readahead into page cache
SYNOPSIS #include <fcntl.h>
ssize_t readahead(int fd, off64_t *offset, size_t count);
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