I've been working with iSER trying to maximize performance. I have two FDR Infiniband cards (three ports total) and I've created multiple address on the target and configured 12 paths from the initiator. The iSER target is served up from a RAM disk. With the 4.4 kernel I'm able to pretty much saturate the links (4.1 million seq 4K read IOPs 15.7 GB/s) using multipathd. With the same configuration on 4.6, I'm only able to get 3.3 million IOPs or 12.8 GB/s. Running perf top on the target and initiator, I'm seeing the target is dominated by 73.89% [kernel] [k] memcpy_rems 1.35% [kernel] [k] get_page_from_freelist ... which is the same with 4.4. Perf top on the target has: 13.01% [kernel] [k] copy_user_enhanced_fast_string 8.48% [kernel] [K] __blk_recalc_re_segments 5.35% [kernel] [k] native_queued_spin_lock_slowpath ... I don't recall what the initiator had on 4.4. Single path performance has increase by about 5% which is nice, but two path performance is about 50% that of the 4.4 kernel. Three paths and greater are around 80% the 4.4 performance. Any ideas on what could have caused the performance issues on 4.6? Is there some additional information I can provide that would be useful? Thanks, ---------------- Robert LeBlanc PGP Fingerprint 79A2 9CA4 6CC4 45DD A904 C70E E654 3BB2 FA62 B9F1 -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
