08/11/2022 15:30, Morten Brørup: > > From: Thomas Monjalon [mailto:tho...@monjalon.net] > > 08/11/2022 12:25, Morten Brørup: > > > From: Morten Brørup > > > > From: Konstantin Ananyev [mailto:konstantin.anan...@huawei.com] > > > > Sent: Tuesday, 8 November 2022 10.20 > > > > > +#ifdef RTE_LIBRTE_MEMPOOL_STATS > > > > > +#define RTE_MEMPOOL_CACHE_STAT_ADD(cache, name, n) (cache)- > > >stats.name += n > > > > > > > > As Andrew already pointed, it needs to be: ((cache)->stats.name += > > (n)) > > > > Apart from that, LGTM. > > > > Series-Acked-by: Konstantin Ananyev <konstantin.anan...@huawei.com> > > > > > > @Thomas, this series should be ready to apply... it now has been: > > > Reviewed-by: (mempool maintainer) Andrew Rybchenko > > <andrew.rybche...@oktetlabs.ru> > > > Reviewed-By: Mattias Rönnblom <mattias.ronnb...@ericsson.com> > > > Acked-by: Konstantin Ananyev <konstantin.anan...@huawei.com> > > > > Being acked does not mean it is good to apply in -rc3. > > I understand that the RFC/v1 of this series was formally too late to make it > in 22.11, so I will not complain loudly if you choose to omit it for 22.11. > > With two independent reviews, including from a mempool maintainer, I still > have some hope. Also considering the risk assessment below. ;-) > > > Please tell what is the benefit for 22.11 (before/after and condition). > > Short version: With this series, mempool statistics can be used in > production. Without it, the performance cost (mempool_perf_autotest: -74 %) > is prohibitive! > > Long version: > > The patch series provides significantly higher performance for mempool > statistics, which are readable through rte_mempool_dump(FILE *f, struct > rte_mempool *mp). > > Without this series, you have to set RTE_LIBRTE_MEMPOOL_DEBUG at build time > to get mempool statistics. RTE_LIBRTE_MEMPOOL_DEBUG also enables protective > cookies before and after each mempool object, which are all verified on > get/put from the mempool. According to mempool_perf_autotest, the performance > cost of mempool statistics (by setting RTE_LIBRTE_MEMPOOL_DEBUG) is a 74 % > decrease in rate_persec for mempools with cache (i.e. mbuf pools). > Prohibitive for use in production! > > With this series, the performance cost of mempool statistics (by setting > RTE_LIBRTE_MEMPOOL_STATS) in mempool_perf_autotest is only 6.7 %, so mempool > statistics can be used in production. > > > Note there is a real risk doing such change that late. > > Risk assessment: > > The patch series has zero effect unless either RTE_LIBRTE_MEMPOOL_DEBUG or > RTE_LIBRTE_MEMPOOL_STATS are set when building. They are not set in the > default build.
If theses build flags are not set, there is no risk and no benefit. But if they are set, there is a risk of regression, for the benefit of an increased performance of a debug feature. I would say it is better to avoid any functional regression in a debug feature at this stage. Any other opinion?
