[PATCH] Revert "lib: sparse: Make CHUNK_TYPE_RAW buffer aligned"

[Tom Rini]

On Fri, Jun 16, 2023 at 03:50:06PM +0200, Mattijs Korpershoek wrote:
> On ven., juin 16, 2023 at 13:56, Mattijs Korpershoek <mkorpershoek at baylibre.com> wrote:
> 
> > Hi Gary, Sean,
> >
> > On lun., nov. 21, 2022 at 10:09, Sean Anderson <sean.anderson at seco.com> 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.
> 
> Answering to myself here. My attempt of solving this problem has been
> submitted here:
> 
> https://lore.kernel.org/r/20230616-sparse-flash-fix-v1-1-6bafeacc567b@baylibre.com

Thanks for digging in to this!

-- 
Tom
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