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a=lCpzRmAYbLLaTzLvsPZ7Mbvzbb8=:19 a=xqWC_Br6kY4A:10 a=wP3pNCr1ah4A:10 a=GoEa3M9JfhUA:10 a=VkNPw1HP01LnGYTKEx00:22 a=Z4Rwk6OoAAAA:8 a=yPCof4ZbAAAA:8 a=QWp4f3afz0_u6ju5zfsA:9 a=HkZW87K1Qel5hWWM3VKY:22 cc=ntf awl=host:13654 X-Proofpoint-ORIG-GUID: pyZEd82NaGoahJXA1Q_IrO85dKskevN1 X-Proofpoint-GUID: pyZEd82NaGoahJXA1Q_IrO85dKskevN1 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUxMjE3MDE1NyBTYWx0ZWRfXwcVttYPCn8y2 1ribskZG1YzudPDpR3vQ5w+B06WWTq8jFzej6rEk9oYuTNHgAHhIss11Iv9CdjnTW0UAK7UXVPT seeyStXMyMyPz+vxqZrg6Rt2ksbcpj/EIj/58Y/TMRd6qpqeyIHn9mMJgp6EbV/fcZidcz/s9GX 44jsCRR3x6djbNhAHrb3xeZxlwTWsVTHlOxM0/6OJJutqA/eixOXXPKfZGKgPdAR+Q/RSJQ99Ts W8QE5XM9RGGS2mT2pbN2mnh4IVwRpC4YcJxebya/o3cd8qJ4N7OLB+OYf5J1pnrll5q7XXpCXgW sc/tw8/3EPvaaKzb2EhYgQsSLj/9qIYz/M98eI80VVSEkUIEx+n82+tGPdHp2/98UnVUj/nv6eV cD6ZubkTFcTtKy3usWtmLisDkWIV2wAgLuc0viBEiRkOBPXy9Q4= Andrew Morton writes: > On Wed, 17 Dec 2025 00:48:50 -0800 Ankur Arora wrote: > >> > At 42GB/sec, 32MB will take less than a >> > millisecond, yes? I'm not aware of us really having any latency >> > targets in these preemption modes, but 1 millisecond sounds pretty >> > good. >> >> Agreed. The only complaint threshold I see is 100ms (default value of >> sysctl_resched_latency_warn_ms) which is pretty far from ~1ms. >> >> And having a threshold of 32MB might benefit other applications since >> we won't be discarding their cachelines in favour of filling up the >> cache with zeroes. >> >> I think the only problem cases might be slow uarchs and workloads where >> the memory bus is saturated which might dilate the preemption latency. >> >> And, even if the operation takes say ~20ms, that should still leave us >> with a reasonably large margin. >> (And, any latency senstive users are probably not running with >> preempt=none/voluntary.) > > So I think you're saying that yes, we should increase the chunk size? Yeah. > If so, what's the timing on that? It would be nice to do it in the > current -rc cycle for testing reasons and so the changelogs can be > updated to reflect the altered performance numbers. I can send out an updated version of this patch later today. I think the only real change is updating the constant and perf stats motivating the chunk size value of 32MB. Anything else you also think needs doing for this? -- ankur