Hi Maya, I didn't see about "[PATCH v5 1/3]mmc: core: Add support for idle time BKOPS" at mailing. Could you check the patch set? Best Regards, Jaehoon Chung On 01/11/2013 05:15 AM, Maya Erez wrote: > Devices have various maintenance operations need to perform internally. > In order to reduce latencies during time critical operations like read > and write, it is better to execute maintenance operations in other > times - when the host is not being serviced. Such operations are called > Background operations (BKOPS). > The device notifies the status of the BKOPS need by updating BKOPS_STATUS > (EXT_CSD byte [246]). > > According to the standard a host that supports BKOPS shall check the > status periodically and start background operations as needed, so that > the device has enough time for its maintenance operations. > > This patch adds support for this periodic check of the BKOPS status. > Since foreground operations are of higher priority than background > operations the host will check the need for BKOPS when it is idle, > and in case of an incoming request the BKOPS operation will be > interrupted. > > When the mmcqd thread is idle, a delayed work is created to check the > need for BKOPS. The time to start the delayed work can be set by the host > controller. If this time is not set, a default time is used. > If the card raised an exception with need for urgent BKOPS (level 2/3) > a flag will be set to indicate MMC to start the BKOPS activity when it > becomes idle. > > Since running the BKOPS too often can impact the eMMC endurance, the card > need for BKOPS is not checked every time MMC is idle (despite of cases of > exception raised). In order to estimate when is the best time to check > for BKOPS need the host will take into account the card capacity and > percentages of changed sectors in the card. A future enhancement can be to > check the card need for BKOPS only in case of random activity. > > This patch is based on the periodic BKOPS implementation in version 8 of "support BKOPS feature for eMMC" patch. > The patch was modified to answer the following issues: > - Since mmc_start_bkops is called from two contexts now, mmc_claim_host was moved to the beginning of the function > - Also, the check of doing_bkops should be protected when determing if an HPI is needed due to the same reason. > > Changes in v5: > - Do not allow BKOPS operation in all levels to be blocking > - Change the periodic check for BKOPS need to be based on percentage of changed sector > - Add BKOPS statistics > > Changes in v4: > - Separate the polling for BKOPS completion to a different patch > - add a flag to indicate if polling for card completion is required > > Changes in v3: > - Move the call to stop_bkops to block.c. > This allows us to remove the mmc_claim_host from inside the function and doesn't cause additional degradation > due to un-neccessary calim host operation > > Changes in v2: > - Check the number of written / discarded sectors as the trigger for checking the BKOPS need. > - Code review fixes > > Maya Erez (3): > mmc: core: Add support for idle time BKOPS > mmc: allow the host controller to poll for BKOPS completion > mmc: core: Add MMC BKOPS statistics and debugfs ability to print them > > Documentation/mmc/mmc-dev-attrs.txt | 9 + > drivers/mmc/card/block.c | 96 ++++++++++++- > drivers/mmc/card/queue.c | 2 + > drivers/mmc/core/bus.c | 2 + > drivers/mmc/core/core.c | 286 +++++++++++++++++++++++++++++++---- > drivers/mmc/core/debugfs.c | 114 ++++++++++++++ > drivers/mmc/core/mmc.c | 20 +++ > include/linux/mmc/card.h | 64 ++++++++- > include/linux/mmc/core.h | 5 + > include/linux/mmc/host.h | 2 +- > 10 files changed, 563 insertions(+), 37 deletions(-) > -- 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
