On 2020/7/3 7:00, Song Liu wrote:
On Thu, Jul 2, 2020 at 5:05 AM Yufen Yu <yuyufen@xxxxxxxxxx> wrote:Hi, all For now, STRIPE_SIZE is equal to the value of PAGE_SIZE. That means, RAID5 will issue each bio to disk at least 64KB when PAGE_SIZE is 64KB in arm64. However, filesystem usually issue bio in the unit of 4KB. Then, RAID5 may waste resource of disk bandwidth. To solve the problem, this patchset try to set stripe_size as a configuare value. The default value is 4096. We will add a new sysfs entry and set it by writing a new value, likely: echo 16384 > /sys/block/md1/md/stripe_sizeHigher level question: do we need to support page size that is NOT 4kB times power of 2? Meaning, do we need to support 12kB, 20kB, 24kB, etc. If we only supports, 4kB, 8kB, 16kB, 32kB, etc. some of the logic can be simpler.
Yeah, I think we just support 4kb, 8kb, 16kb, 32kb... is enough. But Sorry that I don't know what logic can be simpler in current implementation. I mean it also need to allocate page, and record page offset. Thanks, Yufen
