On Wed, Dec 4, 2019 at 7:13 PM Zhengyuan Liu <liuzhengyuan@xxxxxxxxxx> wrote:
>
> There are several algorithms available for raid6 to generate xor and syndrome
> parity, including basic int1, int2 ... int32 and SIMD optimized implementation
> like sse and neon. To test and choose the best algorithms at the initial
> stage, we need provide enough disk data to feed the algorithms. However, the
> disk number we provided depends on page size and gfmul table, seeing bellow:
>
> int __init raid6_select_algo(void)
> {
> const int disks = (65536/PAGE_SIZE) + 2;
> ...
> }
>
> So when come to 64K PAGE_SIZE, there is only one data disk plus 2 parity disk,
> as a result the chosed algorithm is not reliable. For example, on my arm64
> machine with 64K page enabled, it will choose intx32 as the best one, although
> the NEON implementation is better.
I think we can fix this by simply change raid6_select_algo()? We still have
#define STRIPE_SIZE PAGE_SIZE
So testing with PAGE_SIZE represents real performance.
Thanks,
Song
