Hi Gary, Sean, On lun., nov. 21, 2022 at 10:09, Sean Anderson <[email protected]> wrote:
> On 11/21/22 09:50, Gary Bisson wrote: >> Hi, >> >> On Fri, Nov 18, 2022 at 10:36:58AM -0500, Sean Anderson wrote: >>> On 11/18/22 07:13, Gary Bisson wrote: >>> > This reverts commit 62649165cb02ab95b57360bb362886935f524f26. >>> > >>> > The patch decreased the write performance quite a bit. >>> > Here is an example on an i.MX 8M Quad platform. >>> > - Before the revert: >>> > Sending sparse 'vendor' 1/2 (516436 KB) OKAY [ 5.113s] >>> > Writing 'vendor' OKAY [128.335s] >>> > Sending sparse 'vendor' 2/2 (76100 KB) OKAY [ 0.802s] >>> > Writing 'vendor' OKAY [ 27.902s] >>> > - After the revert: >>> > Sending sparse 'vendor' 1/2 (516436 KB) OKAY [ 5.310s] >>> > Writing 'vendor' OKAY [ 18.041s] >>> > Sending sparse 'vendor' 2/2 (76100 KB) OKAY [ 1.244s] >>> > Writing 'vendor' OKAY [ 2.663s] >>> > >>> > Considering that the patch only moves buffer around to avoid a warning >>> > message about misaligned buffers, let's keep the best performances. >>> >>> So what is the point of this warning? >> >> Well the warning does say something true that the cache operation is not >> aligned. Better ask Simon as he's the one who changed the print from a >> debug to warn_non_spl one: >> bcc53bf0958 arm: Show cache warnings in U-Boot proper only >> >> BTW, in my case I couldn't see the misaligned messages, yet I saw the >> performance hit described above. I also reproduce this problem on AM62x SK EVM. Before the revert: Sending sparse 'super' 1/2 (768793 KB) OKAY [ 23.954s] Writing 'super' OKAY [ 75.926s] Sending sparse 'super' 2/2 (629819 KB) OKAY [ 19.641s] Writing 'super' OKAY [ 62.849s] Finished. Total time: 182.474s After the revert: Sending sparse 'super' 1/2 (768793 KB) OKAY [ 23.895s] Writing 'super' OKAY [ 12.961s] Sending sparse 'super' 2/2 (629819 KB) OKAY [ 19.562s] Writing 'super' OKAY [ 12.805s] Finished. Total time: 69.327s And like Gary, I did not observe the misaligned messages. Did we come up with a solution for this performance regression? I will continue looking on my end but please let me know if you already solved this. Thanks, Matijs > > Maybe it is better to keep this as a Kconfig? Some arches may support > unaligned access but others may not. I wonder if we have something like > this already. > > --Seam
