Hi Doug / Sonny New year greetings!! On Sat, Jan 3, 2015 at 4:37 AM, Doug Anderson <dianders@xxxxxxxxxxxx> wrote: > Alim, > > On Mon, Dec 22, 2014 at 4:12 AM, Alim Akhtar <alim.akhtar@xxxxxxxxxxx> wrote: >> From: Seungwon Jeon <tgih.jun@xxxxxxxxxxx> >> >> Even though 1MB is reserved for descriptor table in IDMAC, >> the dw_mmc host driver is allowed to receive only maximum >> 128KB block length in one request. This is caused by setting >> improper max_blk_count. It needs to be e adjusted so that >> descriptor table is used fully. It is found that the performance >> is improved with the increased the max_blk_count. >> >> Signed-off-by: Seungwon Jeon <tgih.jun@xxxxxxxxxxx> >> Acked-by: Jaehoon Chung <jh80.chung@xxxxxxxxxxx> >> Signed-off-by: Alim Akhtar <alim.akhtar@xxxxxxxxxxx> >> --- >> drivers/mmc/host/dw_mmc.c | 4 ++-- >> 1 file changed, 2 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c >> index 64ea042..a1b80e5 100644 >> --- a/drivers/mmc/host/dw_mmc.c >> +++ b/drivers/mmc/host/dw_mmc.c >> @@ -2332,9 +2332,9 @@ static int dw_mci_init_slot(struct dw_mci *host, unsigned int id) >> #ifdef CONFIG_MMC_DW_IDMAC >> mmc->max_segs = host->ring_size; >> mmc->max_blk_size = 65536; >> - mmc->max_blk_count = host->ring_size; >> mmc->max_seg_size = 0x1000; >> - mmc->max_req_size = mmc->max_seg_size * mmc->max_blk_count; >> + mmc->max_req_size = mmc->max_seg_size * host->ring_size; >> + mmc->max_blk_count = mmc->max_req_size / 512; > > The numbers are a little different than the ones you and Sonny arrived > at about a year ago at > <https://chromium-review.googlesource.com/#/c/176488/> > > You end up with the same max_req_size I think, but it looks as if > max_blk_count is 0x800 in your series and ix 0xffff in the one from a > year ago. Do you have any explanation for why it is max_req_size / > 512? > Before taking this patch, I went over all the discussions that had happened in past http://marc.info/?l=linux-mmc&m=133039478518090&w=2 (way back in 2012) http://www.spinics.net/lists/linux-mmc/msg25549.html and http://www.spinics.net/lists/linux-mmc/msg25797.html and the last one was having an ACK from maintainer. Having said that, I did check the performance number with current patch which has landed and with one which sets max_blk_count as 0xFFFF. And both given exactly the same numbers on peach-pi (Write: ~52MB/s and Read: ~146MB/s (HS200) using iozone), I checked it a bit more and found that in both the case max_hw_sectors_kb is set to 1024 (max request size to block layer) and max_hw_sectors_kb is the one which actually affect the Performance numbers and max_hw_sectors_kb is set as blk_queue_max_hw_sectors(mq->queue, min(host->max_blk_count, host->max_req_size / 512)); In case of 64bit IDMAC (one on exynos7) which given a different value for "ring_size", both the patches set the same max_hw_sectors_kb (512 in this case) Do you see some performance degradation with some other variants of dw_mmc host controller with current ToT? Sonny, I ran iozone like: iozone -az -i0 -i1 -I -s 10M -f /home/test (on eMMC) > -Doug -- Regards, Alim -- 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
