On Tue, Jul 05, 2022 at 11:45:29AM +0800, Wen Yang wrote: > > > 在 2022/7/4 下午11:59, Greg Kroah-Hartman 写道: > > On Mon, Jul 04, 2022 at 11:45:08PM +0800, Wen Yang wrote: > > > From: Peter Zijlstra <peterz@xxxxxxxxxxxxx> > > > > > > commit ddd07b750382adc2b78fdfbec47af8a6e0d8ef37 upstream. > > > > > > CAT has happened, WBINDV is bad (even before CAT blowing away the > > > entire cache on a multi-core platform wasn't nice), try not to use it > > > ever. > > > > > > Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> > > > Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> > > > Reviewed-by: Dave Hansen <dave.hansen@xxxxxxxxx> > > > Cc: Bin Yang <bin.yang@xxxxxxxxx> > > > Cc: Mark Gross <mark.gross@xxxxxxxxx> > > > Link: https://lkml.kernel.org/r/20180919085947.933674526@xxxxxxxxxxxxx > > > Cc: <stable@xxxxxxxxxxxxxxx> # 4.19.x > > > Signed-off-by: Wen Yang <wenyang@xxxxxxxxxxxxxxxxx> > > > --- > > > arch/x86/mm/pageattr.c | 18 ++---------------- > > > 1 file changed, 2 insertions(+), 16 deletions(-) > > > > > > diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c > > > index 101f3ad0d6ad..ab87da7a6043 100644 > > > --- a/arch/x86/mm/pageattr.c > > > +++ b/arch/x86/mm/pageattr.c > > > @@ -239,26 +239,12 @@ static void cpa_flush_array(unsigned long *start, int numpages, int cache, > > > int in_flags, struct page **pages) > > > { > > > unsigned int i, level; > > > -#ifdef CONFIG_PREEMPT > > > - /* > > > - * Avoid wbinvd() because it causes latencies on all CPUs, > > > - * regardless of any CPU isolation that may be in effect. > > > - * > > > - * This should be extended for CAT enabled systems independent of > > > - * PREEMPT because wbinvd() does not respect the CAT partitions and > > > - * this is exposed to unpriviledged users through the graphics > > > - * subsystem. > > > - */ > > > - unsigned long do_wbinvd = 0; > > > -#else > > > - unsigned long do_wbinvd = cache && numpages >= 1024; /* 4M threshold */ > > > -#endif > > > BUG_ON(irqs_disabled() && !early_boot_irqs_disabled); > > > - on_each_cpu(__cpa_flush_all, (void *) do_wbinvd, 1); > > > + flush_tlb_all(); > > > - if (!cache || do_wbinvd) > > > + if (!cache) > > > return; > > > /* > > > -- > > > 2.19.1.6.gb485710b > > > > > > > Why is this needed on 4.19.y? What problem does it solve, it looks only > > like an optimization, not a bugfix. > > > > And if it's a bugfix, why only 4.19.y, why not older kernels too? > > > > We need more information here please. > > > > On a 128-core Intel(R) Xeon(R) Platinum 8369B CPU @ 2.90GHz server, when the > user program frequently calls nv_alloc_system_pages to allocate large > memory, it often causes a delay of about 200 milliseconds for the entire > system. In this way, other latency-sensitive tasks on this system are > heavily impacted, causing stability issues in large-scale clusters as well. > > nv_alloc_system_pages > -> _set_memory_array > -> change_page_attr_set_clr > -> cpa_flush_array > -> on_each_cpu(__cpa_flush_all, (void *) do_wbinvd, 1); > > > This patch can be directly merged into the 4.19 kernel to solve this > problem, and most of the machines in our production environment are 4.19 > kernels. Ah. So what has changed from last year when I rejected this then: https://lore.kernel.org/all/9c415df9-9575-8217-03e9-a6bbf20a491a@xxxxxxxxxxxxxxxxx/T/#m06369d080fa97eda3dd6a8eaf54a8ca2d430b3ab Please do not try to submit previously-rejected patches, that is very disingenuous. greg k-h
