Hi Christian,
On 04/09/2018 07:48 AM, Christian König wrote:
Am 06.04.2018 um 17:30 schrieb Jean-Marc Valin:
Hi Christian,
Is there a way to turn off these huge pages at boot-time/run-time?
Only at compile time by not setting CONFIG_TRANSPARENT_HUGEPAGE.
Any reason why echo never > /sys/kernel/mm/transparent_hugepage/enabled doesn't solve the problem?
Also, I assume that disabling CONFIG_TRANSPARENT_HUGEPAGE will disable them for everything and not just what your patch added, right?
I'm not sure what you mean by "We mitigated the problem by avoiding the slow coherent DMA code path on almost all platforms on newer kernels". I tested up to 4.16 and the performance regression is just as bad as it is for 4.15.
Indeed 4.16 still doesn't have that. You could use the amd-staging-drm-next branch or wait for 4.17.
Is there a way to pull just that change or is there too much interactions with other changes?
That isn't related to the GFX hardware, but to your CPU/motherboard and whatever else you have in the system.
Well, I have an nvidia GPU in the same system (normally only used for CUDA) and if I use it instead of my RX 560 then I'm not seeing any performance issue with 4.15.
Some part of your system needs SWIOTLB and that makes allocating memory much slower.
What would that part be? FTR, I have a complete description of my system at https://jmvalin.dreamwidth.org/15583.html
I don't know if it's related, but I can maybe see one thing in common between my machine and the Core 2 Quad from the other bug report and that's the "NUMA part". I have a dual-socket Xeon and (AFAIK) the Core 2 Quad is made of two two-core CPUs glued together with little communication between them.
Intel doesn't use TTM because they don't have dedicated VRAM, but the open source nvidia driver should be affected as well.
I'm using the proprietary nvidia driver (because CUDA). Is that supposed to be affected as well?
We already mitigated that problem and I don't see any solution which will arrive faster than 4.17.
Is that supposed to make the slowdown unnoticeable or just slightly better?
The only quick workaround I can see is to avoid firefox, chrome for example is reported to work perfectly fine.
Or use an unaffected GPU/driver ;-)
Cheers,
Jean-Marc