Hello, all. The following patch-set includes enhancements to the async_tx api and modifications to md-raid6 to issue memory copies and parity calculations asynchronously. Thus we may process copy operations and RAID-6 calculations on the dedicated DMA engines accessible with ASYNC_TX API, and, as a result off-load CPU, and improve the performance. The most impressive performance improvement results are being achieved with big size of strips (i.e. PAGE_SIZE). Here are the comparative results of the RAID-6 full-stripe write throuputs with different strip size values (4KB/16KB/64KB): (a) old s/w Linux RAID-6: 04K: 36 MBps; 16K: 39 MBps; 64K: 40 MBps; (b) asynchronous s/w RAID-6: 04K: 32 MBps; 16K: 48 MBps; 64K: 48 MBps; (c) asynchronous h/w accelerated RAID-6: 04K: 48 MBps; 16K: 94 MBps; 64K: 114 MBps. The example of the test commands used, say, in the 4KB case: # mdadm -C /dev/md0 -l6 -c 16 -n 6 -z 1024000 /dev/sd[a-f] # xdd -op write -kbytes 64000 -reqsize 64 -dio -syncwrite -target /dev/md0 Admittedly, the 4K case for items (a) and (b) above looks not good, at least in the RAID-5 case we do not have even such a small degradation. So, perhaps there are some ways of further improvements in the RAID-6 code. Any suggestions would be greatly appreciate. As far as the patch-set itself is concerned, its division (as well as the most of the code) was based on the RAID-5 patch-set posted to ML by Dan Williams on 07.06.27. The patches were generated against the 28b752d44a3696cde1d6b9790d7ae3b324d11571 commit-id ["raid5: use stripe_queues to prioritize the "most deserving" requests (rev8)"] of git://lost.foo-projects.org/~dwillia2/git/iop "md-for-linus" branch. To reduce the code duplication in the raid driver this patch-set modifies some raid-5 functions to make them possible to use in the raid-6 case. - raid-6 shares the following functions with raid-5 (no specific division): ops_run_io(); async_copy_data(); ops_complete_biofill(); ops_run_biofill(); ops_complete_postxor(); - the following functions require sub-division inside: ops_complete_compute() [based on ops_complete_compute5()]; ops_run_biodrain(); ops_complete_write(); ops_run_postxor(); ops_complete_check(); raid_run_ops() [based on raid5_run_ops()] - the following functions are raid-5/6 specific only: ops_run_compute6_1(); ops_run_compute6_2(); ops_run_check5() [renamed from ops_run_check()]; ops_run_check6(); The patch-set can be broken down into thee following main categories: 1) Additions to ASYNC_TX API (patches 1-2) 2) RAID-6 implementation (patches 3-11) 3) ppc440spe ADMA driver (patch 12) Here are the ingredients: [md-raid6-accel PATCH 01/12] async_tx: PQXOR implementation [md-raid6-accel PATCH 02/12] async_tx: RAID-6 recovery implementation [md-raid6-accel PATCH 03/12] md: run stripe operations outside the lock [md-raid6-accel PATCH 04/12] md: common handle_stripe6() infrastructure [md-raid6-accel PATCH 05/12] md: req/comp logic for async write operations [md-raid6-accel PATCH 06/12] md: req/comp logic for async compute operations [md-raid6-accel PATCH 07/12] md: req/comp logic for async check operations [md-raid6-accel PATCH 08/12] md: req/comp logic for async read operations [md-raid6-accel PATCH 09/12] md: req/comp logic for async expand operations [md-raid6-accel PATCH 10/12] md: req/comp logic for async I/O operations [md-raid6-accel PATCH 11/12] md: remove unused functions [md-raid6-accel PATCH 12/12] adma: ppc440spe DMA engines driver -- Yuri Tikhonov, Senior Software Engineer Emcraft Systems, www.emcraft.com - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
