Messages in this thread | ![/](/images/icornerl.gif) | | From | "David Schwartz" <> | Subject | RE: Is there a way to turn file caching off ? | Date | Wed, 18 Apr 2001 11:21:46 -0700 |
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It's insignificant. If we assume the caching isn't helping, that means each 'non-recent' page access results in an IO operation. The cost of an IO operation (a millisecond or more) is so much in comparison to the cost of a primary cache miss (less than a microsecond) that avoiding a ferw primary cache misses per IO isn't likely to make any measurable difference.
DS
-----Original Message----- From: lchavet@smo.av.com [mailto:lchavet@smo.av.com]On Behalf Of Laurent Chavet Sent: Wednesday, April 18, 2001 1:21 AM To: David Schwartz Cc: linux-kernel@vger.kernel.org Subject: Re: Is there a way to turn file caching off ?
Since the speed already drops before even writing to disk, I was thinking that for "large memory" the management of the tree that contain which pages are cached becomes high (since the tree is large and probably doesn't fit in primary cache). So if you can limit the size of what you cache, you limit the size of the tree -> you limit the time spent in the tree. (by the way I'm using both 2.4.2 that come with RedHat 7.1 and 2.4.4 pre 3 and see the same thing). Laurent
David Schwartz wrote: > Is there a way to turn file caching off, or at least limit its size ? > > Thanks, > > Laurent Chavet What benefit do you think you would get by limiting its size? All that would do is ensure you hit the cache thrashing point sooner. DS -- Laurent Chavet
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