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charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 7BDF64000F X-Stat-Signature: uu4c7tkbh5j6smrzykjpgsx7io9gjjsa X-Rspam-User: X-HE-Tag: 1727885649-785540 X-HE-Meta: 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 TXC3u+Q7 mp8cFTFBnGntRlleJzj/FeIBV3pLgLdzjuSWVp9Mhsu5WuXCC61yPPwlhuFM5NJis8ajljbHRJdB4qjOQmqIKNbF2VttUb7kEP2AW97SJEJvxenPFgm284YZcH01Y8fpi/A8gnFboCxJC6fFi4cQj89q1F8I9yiZcWDm6QJ86ThmvMuiep6FZRtpyG4psqhBJM7ZUJag/aj6L2b3mWDeUo+YdDstYTYDEHLSLPPj2cw/lX4Tx3BDymVTXGQkjzF/pOGVrfGNcSuHCOOTfqc+yaIGWu/MhOBgB6AdSd1aZBlWmSroCrgwgJMNMn93Kmfc90QPUOQfvzbHRFm5vDcBBAowa1wJBbadXqj4+3PfClqxrGFifwOaDaIRqHSIFBR8c5386DXjMfHiFwZgoDvkeZWQjgLMpliOFaHyKNKdsy95YG+YPNl3dsQtsHKbPC7WyM/uLahehWflJg5GEVu9TgWBSUw== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 10/2/24 10:02 AM, Mathieu Desnoyers wrote: > On 2024-10-02 17:58, Jens Axboe wrote: >> 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. > > Just to make sure: did you use other command line options when starting > the test program (other than -t N ?). I did not, this is literally what I ran: for i in 24 48 96 192 256 512 1024 2048; do echo $i threads; timeout -s INT -k 30 30 ./context_switch1_threads -t $i; done and the numbers I got were very stable between runs and reboots. -- Jens Axboe