Re: [naviserver-devel] memtest

[Vlad S. <vl...@cr...>]

That could be true on Solaris, but in Linux 2.6 mmap/munmap is very fast 
and looking into kernel source it tells you that they conver sbrk ito 
mmap imternally but the different is that mmap is multithreaded-aware 
while sbrk not.

Now, using mmap to allocate block of memory and then re-using that this 
is waht i am doing, but i do not use munmap, still it is possible.
With random allocations from 1-128L, Tcl alloc gives the worst results, 
constantly, which means it is good on small allocations only?

Tcl: 8.4.12, threads 16, loops 500000
starting 16 malloc threads...waiting....done:  3 seconds, 955518 usec
starting 16 ckalloc threads...waiting....done:  4 seconds, 272964 usec
starting 16 _malloc threads...waiting....done:  1 seconds, 890566 usec

I am not trying to re-invent the wheel, it is just accidentally i 
replaced sbrk with mmap and removed mutexes around it and it became much 
faster than what we have now, at least on Linux.

Stephen Deasey wrote:
> On 2/3/06, Vlad Seryakov <vl...@cr...> wrote:
> 
>>Here is the test http://www.crystalballinc.com/vlad/tmp/memtest.c
>>
>>It give very strange results, it works for Linux only because it uses
>>mmap only and it looks like brk uses mmap internally according to Linux
>>2.6.13 kernel and it allows unlimited mmap-ed regions (or as i
>>understand up to vm.max_map_count = 65536).
>>
>>According to this test, when i use random sizes from 0-128k, Tcl
>>allocator gives worse results than Linux malloc. On small amounts
>>ckalloc faster but once over 64k, Linux malloc is faster. And, my small
>>malloc implementaion which is based on first version of Lea's malloc and
>>uses mmap only and supports per-thread memory only beats all mallocs,
>>especially on bigger sizes. It does not crash, even on 5Mil loops, but i
>>am not sure why it is so simple and so effective.
> 
> 
> 
> Have you taken fragmentation into account?
> 
> There's some memory related links in this blog post I read recently:
> 
>     http://primates.ximian.com/~federico/news-2005-12.html#14
> 
> Federico makes a good point: this has all been done before...
> 
> 
> -------------------------------------------------------
> This SF.net email is sponsored by: Splunk Inc. Do you grep through log files
> for problems?  Stop!  Download the new AJAX search engine that makes
> searching your log files as easy as surfing the  web.  DOWNLOAD SPLUNK!
> http://sel.as-us.falkag.net/sel?cmd=k&kid3432&bid#0486&dat1642
> _______________________________________________
> naviserver-devel mailing list
> nav...@li...
> https://lists.sourceforge.net/lists/listinfo/naviserver-devel
> 

-- 
Vlad Seryakov
571 262-8608 office
vl...@cr...
http://www.crystalballinc.com/vlad/