One thing that might be worth noting is that the current CVS version does do some "unintended" COW things. My previous patch (the RECALL -> AGAIN) thing attempted to fix this but has not been applied. Basically, when setting a value that was previously a non-string value (integer, float, etc...) to a string, the string is not copied, it is merely assigned. I didn't look to see if this would affect you, but you might keep it in mind. ----- Original Message ----- From: "Peter Gibbs" <[EMAIL PROTECTED]> To: "Mike Lambert" <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]> Sent: Sunday, August 18, 2002 4:43 PM Subject: Re: [perl #16269] [PATCH] COW...Again and Again
> Here are some timings on my system with your basic stats patch: > These results are taken when the first command input is expected, > having keyed-ahead the N to avoid delays. > > CVS + COW: (using your original cow patch) > Took 36.080085 seconds. A total of 2412496 bytes were allocated > A total of 18 DOD runs were made > A total of 279 collection runs were made > Copying a total of 449220208 bytes > There are 10775 active Buffer structs > There are 88064 total Buffer structs > > Pure CVS : > Took 8.239516 seconds. A total of 105072 bytes were allocated > A total of 165 DOD runs were made > A total of 168 collection runs were made > Copying a total of 12004304 bytes > There are 2470 active Buffer structs > There are 22528 total Buffer structs > > Old 'local' (this is my last version before your refactoring exercise) > Took 4.734133 seconds. A total of 352256 bytes were allocated > A total of 257 DOD runs were made > A total of 6 collection runs were made > Copying a total of 97761 bytes > There are 1311 active Buffer structs > There are 1760 total Buffer structs > > New 'grey' (basically the same as CVS plus the grey1 patch) > Took 4.458817 seconds. A total of 221184 bytes were allocated > A total of 44 DOD runs were made > A total of 42 collection runs were made > Copying a total of 2355521 bytes > There are 2008 active Buffer structs > There are 22528 total Buffer structs > > This is with the random behaviour, but I doubt that makes any > really significant differences. > > I am rather concerned about the total Buffer structs numbers: > your cow version allocates 4x as many as cvs. It doesn't seem > to be anything that should be affected by the cow logic. Does it > get better with your reclaimable changes? From my previous > benchmarks I remember that DOD is one of our most expensive > operations, and that is dependent on the number of allocated > objects. > > Note that I get half the memory usage with grey that you do, > even though we should be running the same code; but it is > still double current cvs. Out of interest, try adding a sweep and > collect in instructions.pasm at label getout, so the reported > active buffers and memory use are as accurate as we can > make them. Which makes me think of something - grey is > ignoring reclaimable to get the size to allocate for the > post-compaction pool, therefore the memory usage is always > going to be higher than is actually needed - are we simply > looking at excess allocation here, rather than excess usage? > If so, grey will fix it in the next release with paged memory > allocation; and I'm sure you'll think of a solution also. > -- > Peter Gibbs > EmKel Systems > > > >
