Re: Kernel SCM saga..

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Daniel Phillips wrote:
On Friday 08 April 2005 03:05, Rogan Dawes wrote:

Take a look at
http://www.linuxshowcase.org/2001/full_papers/ezolt/ezolt_html/

Abstract

GNU libc's default setting for malloc can cause a significant
performance penalty for applications that use it extensively, such as
Compaq's high performance extended math library, CXML.  The default
malloc tuning can cause a significant number of minor page faults, and
result in application performance of only half of the true potential.


This does not smell like an n*2 suckage, more like n^something suckage. Finding the elephant under the rug should not be hard. Profile?


Lack of hysteresis can do that, with large swats of memory constantly being claimed and returned to the system. One way to implement hysteresis would be based on a decaying peak-based threshold; unfortunately for optimal performance that requires the C runtime to have a notion of time, and in extreme cases even be able to do asynchronous deallocation, but in reality one can probably assume that the rate of malloc/free is roughly constant over time.

	-hpa
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