On Wed, Oct 19, 2022 at 9:30 AM Flavio Leitner <[email protected]> wrote: > > > Hi Mike, > > Thanks for the patch. > > Does this patch need to change this line too? > https://github.com/openvswitch/ovs/blob/31db0e043119cf597d720d94f70ec19cf5b8b7d4/rhel/usr_lib_systemd_system_ovs-vswitchd.service.in#L18 > > > Wouldn't it be better to have a config option that we > can change at runtime? Or perhaps leave it to use the > system's default unless configured to cap the amount?
What I'm worried about here is if OVN is used and a few other things like dnat/snat, the resulting openflow rules can cause a segfault with the system default 2MB stack. The stack conditions aren't really detectable during runtime so increasing the default seemed reasonable to me. It also doesn't seem trivial to me to determine if any given set of OpenFlow rules will or won't cause an explosion in stack usage. > > BTW, I think we use Reported-at: tag instead of Bugzilla:. You're right! I don't know where I came up with that tag. -M > > > fbl > > On Wed, Oct 19, 2022 at 09:01:46AM -0400, Mike Pattrick wrote: > > Previously the minimum thread stack size was always set to 512 kB to > > help accomidate smaller OpenWRT based systems. Often these devices > > don't have a lot of total system memory, so such a limit makes sense. > > > > The default under x86-64 linux is 2MB, this limit is not always enough > > to reach the recursion limits in xlate_resubmit_resource_check(), > > resulting in a segfault instead of a recoverable error. This can happen > > even when the stack size is set up for unlimited expansion when the > > virtaul memory areas of handler threads abut eachother, preventing any > > further expansion. > > > > The solution proposed here is to set a minimum of 4MB on systems with > > more than 4GB of total ram. > > > > Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2104779 > > Signed-off-by: Mike Pattrick <[email protected]> > > --- > > lib/ovs-thread.c | 46 ++++++++++++++++++++++++++++++++++++++++++++-- > > lib/ovs-thread.h | 1 + > > 2 files changed, 45 insertions(+), 2 deletions(-) > > > > diff --git a/lib/ovs-thread.c b/lib/ovs-thread.c > > index 78ed3e970..dbe4a036f 100644 > > --- a/lib/ovs-thread.c > > +++ b/lib/ovs-thread.c > > @@ -478,10 +478,21 @@ ovs_thread_create(const char *name, void > > *(*start)(void *), void *arg) > > * requires approximately 384 kB according to the following analysis: > > * > > https://mail.openvswitch.org/pipermail/ovs-dev/2016-January/308592.html > > * > > - * We use 512 kB to give us some margin of error. */ > > + * We use at least 512 kB to give us some margin of error. > > + * > > + * However, this can cause issues on larger systems with complex > > + * OpenFlow tables. A default stack size of 2MB can result in segfaults > > + * if a lot of clones and resubmits are used. So if the system memory > > + * exceeds some limit then use a 4 MB stack. > > + * */ > > pthread_attr_t attr; > > pthread_attr_init(&attr); > > - set_min_stack_size(&attr, 512 * 1024); > > + > > + if (system_memory() >> 30 > 4) { > > + set_min_stack_size(&attr, 4096 * 1024); > > + } else { > > + set_min_stack_size(&attr, 512 * 1024); > > + } > > > > error = pthread_create(&thread, &attr, ovsthread_wrapper, aux); > > if (error) { > > @@ -680,6 +691,37 @@ count_total_cores(void) > > return n_cores > 0 ? n_cores : 0; > > } > > > > +/* Returns the total system memory in bytes, or 0 if the > > + * number cannot be determined. */ > > +uint64_t > > +system_memory(void) > > +{ > > + static struct ovsthread_once once = OVSTHREAD_ONCE_INITIALIZER; > > + static uint64_t memory; > > + > > + if (ovsthread_once_start(&once)) { > > +#if defined(_WIN32) > > + MEMORYSTATUSEX statex; > > + > > + statex.dwLength = sizeof statex; > > + GlobalMemoryStatusEx(&statex); > > + memory = statex.ullTotalPhys; > > +#elif defined(__linux__) > > + long int page_count = sysconf(_SC_PHYS_PAGES); > > + long int page_size = sysconf(_SC_PAGESIZE); > > + > > + if (page_count > 0 && page_size > 0) { > > + memory = page_count * page_size; > > + } else { > > + memory = 0; > > + } > > +#endif > > + ovsthread_once_done(&once); > > + } > > + > > + return memory; > > +} > > + > > /* Returns 'true' if current thread is PMD thread. */ > > bool > > thread_is_pmd(void) > > diff --git a/lib/ovs-thread.h b/lib/ovs-thread.h > > index aac5e19c9..2ce66b721 100644 > > --- a/lib/ovs-thread.h > > +++ b/lib/ovs-thread.h > > @@ -523,6 +523,7 @@ bool may_fork(void); > > > > int count_cpu_cores(void); > > int count_total_cores(void); > > +uint64_t system_memory(void); > > bool thread_is_pmd(void); > > > > #endif /* ovs-thread.h */ > > -- > > 2.31.1 > > > > _______________________________________________ > > dev mailing list > > [email protected] > > https://mail.openvswitch.org/mailman/listinfo/ovs-dev > > -- > fbl > _______________________________________________ dev mailing list [email protected] https://mail.openvswitch.org/mailman/listinfo/ovs-dev
