Re: Suggestion for laptop suspension

From: Stephen C. Tweedie (
Date: Mon Aug 28 2000 - 08:44:59 EST


On Sun, Aug 27, 2000 at 04:43:54PM +0200, Daniel Phillips wrote:

> There are other good reasons why users should be able to tell the
> kernel to shrink its caches. For example, throwing away the cache to
> force actual device accesses would help determine if low-level file
> and device I/O are working correctly. An example for normal users:
> you might be aware that some big job that filled up the caches is now
> finished, and so the caches can be shrunk immediately instead of
> piecemeal as other applications try to get memory. As user, you are
> sometimes in a much better position to know when to shrink the caches
> than the OS is.

Not a good plan. You really want to be able to do this on a per-file
basis, not per-device. You want to be able to do things like open a
file O_RSYNC and know that the kernel will read from physical media
instead of from cache, or to open it O_DIRECT and know that the data
will not be cached at all. There are so many uses for that sort of
thing that trying to fix it by adding block device or system-wide
virtual memory calls is really not going to address the needs


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