> Am 27.06.2016 um 14:39 schrieb Stefan Hajnoczi <stefa...@gmail.com>: > >> On Fri, Jun 24, 2016 at 12:45:49PM +0200, Peter Lieven wrote: >>> Am 24.06.2016 um 11:58 schrieb Peter Maydell: >>>> On 24 June 2016 at 10:37, Stefan Hajnoczi <stefa...@gmail.com> wrote: >>>>> On Wed, Jun 22, 2016 at 09:56:06PM +0100, Peter Maydell wrote: >>>>>> On 22 June 2016 at 20:55, Peter Lieven <p...@kamp.de> wrote: >>>>>> What makes the coroutine pool memory intensive is the stack size of 1MB >>>>>> per >>>>>> coroutine. Is it really necessary to have such a big stack? >>>>> That reminds me that I was wondering if we should allocate >>>>> our coroutine stacks with MAP_GROWSDOWN (though if we're >>>>> not actually using 1MB of stack then it's only going to >>>>> be eating virtual memory, not necessarily real memory.) >>>> Yes, MAP_GROWSDOWN will not reduce RSS. >>> Right, but then the 1MB of stack as currently allocated isn't >>> going to be affecting RSS either I would have thought (except >>> transiently, since we zero it on allocation which will >>> bring it into the RSS until it falls back out again >>> because we don't touch it after that). >> >> What I observe regarding the coroutine pool is really strange. Under I/O load >> while booting the vServer the RSS size is low as expected. If the vServer >> runs >> for some time the RSS size suddenly explodes as if suddenly all the stack >> memory gets >> mapped. This symptom definetely goes away if I disable the pool. >> >> Regarding the coroutine pool I had the following thoughts: >> - mmap the stack so its actually really freed if the coroutine is deleted >> (with MAP_GROWSDOWN or not?) > > This might be an easy fix if malloc is holding memory and not reusing > it.
it is reusing it, but its heavily fragmented as it seems. i am preparing a series to improve the rss usage. hopefully i have sth ready by tomorrow. Peter > > Stefan
