On Sat, Jan 3, 2015 at 4:51 PM, Alim Akhtar <alim.akhtar@xxxxxxxxx> wrote: > 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? Looks like Doug test it and saw a performance improvement on rk3288 Thanks! > > 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
