|Bill Allombert on Sun, 22 Jan 2017 12:12:53 +0100|
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|Re: Use PROT_NONE for unused virtual stack memory|
On Thu, Jan 19, 2017 at 11:41:38PM +0000, Jeroen Demeyer wrote: > On 2017-01-19 13:58, Bill Allombert wrote: > >On Thu, Jan 19, 2017 at 12:27:09PM +0000, Jeroen Demeyer wrote: > >>On 2017-01-19 11:54, Bill Allombert wrote: > >>>This leads to a change of behaviour. Is it intended ? > >> > >>Yes, this is due to changes in new_chunk_resize(). Instead of iteratively > >>doubling, the PARI stack is increased by more than a factor 2 if needed. > > > >The decision about how much to enlarge the stack should be left to > >paristack_resize(0) and not be hard-coded in new_chunk_resize. > >This way it is possible to implement other policies in > >paristack_resize(0). > > It just seemed inefficient to call paristack_resize(0) multiple times > compared to calling it once with a large stack value. Honestly, I think it's > an irrelevant detail and I don't really care about it. One issue with this policy is that much of the time, the next call to new_chunk will also overflow the stack so this is not really more efficient. It also increases the possibility that the gc_needed mechanism enter a tight loop. Cheers, Bill.