On Wed, Jun 13, 2012 at 12:45 AM, <merez@xxxxxxxxxxxxxx> wrote: > >> S, Venkatraman <svenkatr@xxxxxx> wrote: >>> On Mon, Jun 11, 2012 at 1:53 PM, Seungwon Jeon <tgih.jun@xxxxxxxxxxx> >>> wrote: >>> > This patch adds packed command feature of eMMC4.5. >>> > The maximum number for packing read(or write) is offered >>> > and exception event relevant to packed command which is >>> > used for error handling is enabled. If host wants to use >>> > this feature, MMC_CAP2_PACKED_CMD should be set. >>> > >>> > Signed-off-by: Seungwon Jeon <tgih.jun@xxxxxxxxxxx> >>> >>> Can you please post some clear performance benchmarks with your patchset >>> ? >>> Given that #merez claims to see a significant performance drop for >>> reads, it will be >>> good to compare notes. >>> If it's not too much trouble, both CFQ and deadline scheduler figures >>> would be useful, on a >>> set of read only, write only and parallel read write usecases. >>> >>> I can also try to replicate your results if you can publish the exact >>> configuration you used >>> for testing (example: iozone parameters) >> I'm checking the merez's result. >> Currently packed command is effective on write. >> When running packed write with iozone, there is 25% performance gains. >> (ex: iozone -az -i0 -I -s 10m -f /target/test -e) >> > Our tests shows performance gain of 50-60% in scenarios of only write lmdd > operations. > > As I mentioned in the write packing control thread the degradation of read > performance in case of mix read/write operations appears also without > write packing. Therefore I don't think it should stop us from approving > the write packing patch, that gives a significant improvement to the write > performance. > The read performance degradation should be resolved regardless of the > write packing patch. > One further question - when you say "degradation of read performance in case of mix read/write operations appears also without write packing", what exactly does that mean? Degradation w.r.to to read-only test ? Or any expected throughput ? If the scenario you mention is accurate, I was actually thinking that we should recommend to merge read packing first, then merge write packing once the read performance issue is well understood. I am all for better performance with packing control etc, but the overall code complexity is really increasing more than necessary. I want to make sure that it is really worth the effort. Thanks, Venkat. -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
