On 28/07/2025 16:39, Manivannan Sadhasivam wrote:
On Mon, Jul 28, 2025 at 08:06:21PM GMT, Manivannan Sadhasivam wrote:
- Nitin
Really added Nitin now.
BTW what about MCQ on SM8650 ? it's probably the real fix here...
Neil
On Thu, Jul 24, 2025 at 02:38:30PM GMT, André Draszik wrote:
On Thu, 2025-07-24 at 13:54 +0200, Neil Armstrong wrote:
On 24/07/2025 13:44, André Draszik wrote:
On Thu, 2025-07-24 at 10:54 +0100, André Draszik wrote:
fio results on Pixel 6: read / 1 job original after this commit min IOPS 4,653.60 2,704.40 3,902.80 max IOPS 6,151.80 4,847.60 6,103.40 avg IOPS 5,488.82 4,226.61 5,314.89 cpu % usr 1.85 1.72 1.97 cpu % sys 32.46 28.88 33.29 bw MB/s 21.46 16.50 20.76
read / 8 jobs original after this commit min IOPS 18,207.80 11,323.00 17,911.80 max IOPS 25,535.80 14,477.40 24,373.60 avg IOPS 22,529.93 13,325.59 21,868.85 cpu % usr 1.70 1.41 1.67 cpu % sys 27.89 21.85 27.23 bw MB/s 88.10 52.10 84.48
write / 1 job original after this commit min IOPS 6,524.20 3,136.00 5,988.40 max IOPS 7,303.60 5,144.40 7,232.40 avg IOPS 7,169.80 4,608.29 7,014.66 cpu % usr 2.29 2.34 2.23 cpu % sys 41.91 39.34 42.48 bw MB/s 28.02 18.00 27.42
write / 8 jobs original after this commit min IOPS 12,685.40 13,783.00 12,622.40 max IOPS 30,814.20 22,122.00 29,636.00 avg IOPS 21,539.04 18,552.63 21,134.65 cpu % usr 2.08 1.61 2.07 cpu % sys 30.86 23.88 30.64 bw MB/s 84.18 72.54 82.62
Given the severe performance drop introduced by the culprit commit, it might make sense to instead just revert it for 6.16 now, while this patch here can mature and be properly reviewed. At least then 6.16 will not have any performance regression of such a scale.
The original change was designed to stop the interrupt handler to starve the system and create display artifact and cause timeouts on system controller submission. While imperfect, it would require some fine tuning for smaller controllers like on the Pixel 6 that when less queues.
Well, the patch has solved one problem by creating another problem. I don't think that's how things are normally done. A 40% bandwidth and IOPS drop is not negligible.
And while I am referencing Pixel 6 above as it's the only device I have available to test, I suspect all < v4 controllers / devices are affected in a similar way, given the nature of the change.
IMO we should just revert the offending commit for 6.16 and see how to properly implement it in the next release. Even with this series, we are not on par with the original IOPS, which is bad for everyone.
- Mani
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