On 10/2/24 9:53 AM, Mathieu Desnoyers wrote: > On 2024-10-02 17:36, Mathieu Desnoyers wrote: >> On 2024-10-02 17:33, Matthew Wilcox wrote: >>> On Wed, Oct 02, 2024 at 11:26:27AM -0400, Mathieu Desnoyers wrote: >>>> On 2024-10-02 16:09, Paul E. McKenney wrote: >>>>> On Tue, Oct 01, 2024 at 09:02:01PM -0400, Mathieu Desnoyers wrote: >>>>>> Hazard pointers appear to be a good fit for replacing refcount based lazy >>>>>> active mm tracking. >>>>>> >>>>>> Highlight: >>>>>> >>>>>> will-it-scale context_switch1_threads >>>>>> >>>>>> nr threads (-t) speedup >>>>>> 24 +3% >>>>>> 48 +12% >>>>>> 96 +21% >>>>>> 192 +28% >>>>> >>>>> Impressive!!! >>>>> >>>>> I have to ask... Any data for smaller numbers of CPUs? >>>> >>>> Sure, but they are far less exciting ;-) >>> >>> How many CPUs in the system under test? >> >> 2 sockets, 96-core per socket: >> >> CPU(s): 384 >> On-line CPU(s) list: 0-383 >> Vendor ID: AuthenticAMD >> Model name: AMD EPYC 9654 96-Core Processor >> CPU family: 25 >> Model: 17 >> Thread(s) per core: 2 >> Core(s) per socket: 96 >> Socket(s): 2 >> Stepping: 1 >> Frequency boost: enabled >> CPU(s) scaling MHz: 68% >> CPU max MHz: 3709.0000 >> CPU min MHz: 400.0000 >> BogoMIPS: 4800.00 >> >> Note that Jens Axboe got even more impressive speedups testing this >> on his 512-hw-thread EPYC [1] (390% speedup for 192 threads). I've >> noticed I had schedstats and sched debug enabled in my config, so I'll have to re-run my tests. > > A quick re-run of the 128-thread case with schedstats and sched debug > disabled still show around 26% speedup, similar to my prior numbers. > > I'm not sure why Jens has much better speedups on a similar system. > > I'm attaching my config in case someone spots anything obvious. Note > that my BIOS is configured to show 24 NUMA nodes to the kernel (one > NUMA node per core complex). Here's my .config - note it's from the stock kernel run, which is why it still has: CONFIG_MMU_LAZY_TLB_REFCOUNT=y set. Have the same numa configuration as you, just end up with 32 nodes on this box. -- Jens Axboe
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