On Fri, Mar 18, 2011 at 03:40:48PM +0100, Corinna Vinschen wrote: >On Mar 18 11:23, Corinna Vinschen wrote: >> On Mar 18 02:08, Christopher Faylor wrote: >> > On Fri, Mar 18, 2011 at 05:47:04AM +0000, Dave Korn wrote: >> > >On 11/03/2011 13:53, Rainer Emrich wrote: >> > > >> > >> I have to be more clear. I increased the heap_chunk_in_mb to 1792 using: >> > >> regtool -i set /HKLM/Software/Cygwin/heap_chunk_in_mb 1792 >> > > >> > > I run with this setting all the time, I guess that's why I haven't seen >> > > this >> > >problem. Before I did that (couple of years back) I also used to get >> > >crashes >> > >building libjava. >> > >> > That setting should have nothing to do with cmalloc(). cmalloc is for >> > Cygwin's internal heap which has nothing to do with that setting. >> > >> > Didn't Corinna already mention this? >> >> In this case the bigger heap seems to avoid the aggressive use of small >> mmap chunks which in turn disallows to raise the cygheap size. Without >> analyzing the whole situation there's not much else to say or do. This >> is YA case which screams loudly for a testcase... > >I created an extensive testcase(*) and it turned out that the current >algorithm to allocate memory on the cygheap is wasting a lot of memory. >Actually it organizes the memory in buckets, each of which cares for a >specific size as a power of 2. So memory on the cygheap is always >allocated in chunks of 4 byte, 8 byte, 16 byte, 32 byte, etc. Plus, >every chunk needs extra 8 byte for bookkeeping.
Right. That's a fairly classic implementation of malloc which was, in this case, implemented by DJ Delorie. I chose that from a few other implementations because it was, at the time, supposed to be the best tradeoff between speed and memory usage. But, back when I implemented the cygheap it wasn't used as much as it is now, which I guess is fairly obvious. cgf -- Problem reports: http://cygwin.com/problems.html FAQ: http://cygwin.com/faq/ Documentation: http://cygwin.com/docs.html Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple