On Tue, Apr 21, 2020 at 5:40 AM Yufen Yu <yuyufen@xxxxxxxxxx> wrote:
>
[...]
> Thus, we provide a configure to set STRIPE_SIZE when PAGE_SIZE is bigger
> than 4096. Normally, default value (4096) can get relatively good
> performance. But if each issued io is bigger than 4096, setting value more
> than 4096 may get better performance.
>
> Signed-off-by: Yufen Yu <yuyufen@xxxxxxxxxx>
I am sorry for the delay response.
> ---
> drivers/md/Kconfig | 18 ++++++++++++++++++
> drivers/md/raid5.h | 4 +++-
> 2 files changed, 21 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/md/Kconfig b/drivers/md/Kconfig
> index d6d5ab23c088..05c5a315358b 100644
> --- a/drivers/md/Kconfig
> +++ b/drivers/md/Kconfig
> @@ -157,6 +157,24 @@ config MD_RAID456
>
> If unsure, say Y.
>
> +config MD_RAID456_STRIPE_SIZE
> + int "RAID4/RAID5/RAID6 stripe size"
> + default "4096"
> + depends on MD_RAID456
> + help
> + The default value is 4096. Just setting a new value when PAGE_SIZE
> + is bigger than 4096. In that case, you can set it as more than
> + 4096, such as 8KB, 16K, 64K, which requires that be a multiple of
> + 4K.
> +
> + When you try to set a big value, likely 64KB on arm64, that means,
> + you know size of each io that issued to raid device is more than
> + 4096. Otherwise just use default value.
> +
> + Normally, using default STRIPE_SIZE can get better performance.
> + Only change this value if you know what you are doing.
> +
> +
> config MD_MULTIPATH
> tristate "Multipath I/O support"
> depends on BLK_DEV_MD
> diff --git a/drivers/md/raid5.h b/drivers/md/raid5.h
> index f90e0704bed9..b0010991bdc8 100644
> --- a/drivers/md/raid5.h
> +++ b/drivers/md/raid5.h
> @@ -472,7 +472,9 @@ struct disk_info {
> */
>
> #define NR_STRIPES 256
> -#define STRIPE_SIZE PAGE_SIZE
> +#define STRIPE_SIZE \
> + ((PAGE_SIZE > 4096 && (CONFIG_MD_RAID456_STRIPE_SIZE % 4096 == 0)) ? \
> + CONFIG_MD_RAID456_STRIPE_SIZE : PAGE_SIZE)
How about we make the config multiple of 4kB? So 4096 will be 1, 8192 will be 2.
Thanks,
Song
