在 2023/3/6 18:05, Greg KH 写道: > On Mon, Mar 06, 2023 at 05:28:41PM +0800, Zhang Qiao wrote: >> >> >> 在 2023/3/6 17:19, Greg KH 写道: >>> On Mon, Mar 06, 2023 at 04:31:57PM +0800, Zhang Qiao wrote: >>>> >>>> >>>> 在 2023/3/5 12:02, Sasha Levin 写道: >>>>> This is a note to let you know that I've just added the patch titled >>>>> >>>>> sched/fair: sanitize vruntime of entity being placed >>>>> >>>>> to the 4.14-stable tree which can be found at: >>>>> http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary >>>>> >>>>> The filename of the patch is: >>>>> sched-fair-sanitize-vruntime-of-entity-being-placed.patch >>>>> and it can be found in the queue-4.14 subdirectory. >>>>> >>>>> If you, or anyone else, feels it should not be added to the stable tree, >>>>> please let <stable@xxxxxxxxxxxxxxx> know about it. >>>>> >>>>> >>>>> >>>>> commit 38247e1de3305a6ef644404ac818bc6129440eae >>>> >>>> Hi, >>>> This patch has significant impact on the hackbench.throughput [1]. >>>> Please don't backport this patch. >>>> >>>> [1] https://lore.kernel.org/lkml/202302211553.9738f304-yujie.liu@xxxxxxxxx/T/#u >>> >>> This link says it made hackbench.throughput faster, not slower, so why >>> would we NOT want it? >> >> Please see this section. In some cases, this patch reset task's vruntime by mistake and >> will lead to wrong results. >> >> >> On Tue, Feb 21, 2023 at 03:34:16PM +0800, kernel test robot wrote: >>> >>> FYI, In addition to that, the commit also has significant impact on the following tests: >>> >>> +------------------+--------------------------------------------------+ >>> | testcase: change | hackbench: hackbench.throughput -8.1% regression | >>> | test machine | 104 threads 2 sockets (Skylake) with 192G memory | >>> | test parameters | cpufreq_governor=performance | >>> | | ipc=socket | >>> | | iterations=4 | >>> | | mode=process | >>> | | nr_threads=100% | >>> +------------------+--------------------------------------------------+ >>> >>> Details are as below: > > So one benchmark did better, by a lot, and one did less, by a little? > Which one matters "more"> > > So Linus's tree now has a regression? Or not? I'm confused. We are Yes, Linus's tree also has a regression, and i have sent a patch[1] for fix this regression. [1]: https://lore.kernel.org/lkml/79850642-ebac-5c23-d32d-b28737dcb91e@xxxxxxxxxx/ thanks. Zhang qiao. > just matching what is in Linus's tree, if it's wrong here, in a stable > tree, it should be wrong there too. If not, please explain why not? > > thanks, > > greg k-h > . >
