Neil, This is another attempt to make raid5 stripe handling multi-threading. Recent workqueue improvement for unbound workqueue looks very promising to the raid5 usage. I had details in the first patch.
The patches are against your tree with patch 'raid5: make release_stripe lockless' and 'raid5: fix stripe release order' but without 'raid5: create multiple threads to handle stripes' My test setup has 7 PCIe SSD, chunksize 8k, stripe_cache_size 2048. If enabling multi-threading, group_thread_cnt is set to 8. randwrite throughput(ratio) unpatch/patch requestsize(sectors) unpatch/patch 4k 1/5.9 8/8 8k 1/5.5 16/13 16k 1/4.8 16/13 32k 1/4.6 18/14 64k 1/4.7 17/13 128k 1/4.2 23/16 256k 1/3.5 41/21 512k 1/3 75/28 1M 1/2.6 134/34 For example, in 1M randwrite test, patched kernel is 2.6x faster, but average request sending to each disk is drop to 34 sectors from 134 sectors long. Currently the biggest problem is request size is dropped, because there are multiple threads dispatching requests. This indicates multi-threading might not be proper for all setup, so I disable it by default in this version. But since throughput is largly improved, I thought this isn't a blocking issue. I'm still working on improving this, maybe schedule stripes from one block plug as a whole. Thanks, Shaohua -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
