On 02/10/17 11:32, Ulf Hansson wrote: > On 22 September 2017 at 14:37, Adrian Hunter <adrian.hunter@xxxxxxxxx> wrote: >> Add CQE support to the block driver, including: >> - optionally using DCMD for flush requests >> - "manually" issuing discard requests >> - issuing read / write requests to the CQE >> - supporting block-layer timeouts >> - handling recovery >> - supporting re-tuning >> >> CQE offers 25% - 50% better random multi-threaded I/O. There is a slight >> (e.g. 2%) drop in sequential read speed but no observable change to sequential >> write. >> >> CQE automatically sends the commands to complete requests. However it only >> supports reads / writes and so-called "direct commands" (DCMD). Furthermore >> DCMD is limited to one command at a time, but discards require 3 commands. >> That makes issuing discards through CQE very awkward, but some CQE's don't >> support DCMD anyway. So for discards, the existing non-CQE approach is >> taken, where the mmc core code issues the 3 commands one at a time i.e. >> mmc_erase(). Where DCMD is used, is for issuing flushes. >> >> For host controllers without CQE support, blk-mq support is extended to >> synchronous reads/writes or, if the host supports CAP_WAIT_WHILE_BUSY, >> asynchonous reads/writes. The advantage of asynchronous reads/writes is >> that it allows the preparation of the next request while the current >> request is in progress. >> >> Signed-off-by: Adrian Hunter <adrian.hunter@xxxxxxxxx> >> --- >> drivers/mmc/core/block.c | 732 ++++++++++++++++++++++++++++++++++++++++++++++- >> drivers/mmc/core/block.h | 8 + >> drivers/mmc/core/queue.c | 427 +++++++++++++++++++++++++-- >> drivers/mmc/core/queue.h | 54 +++- >> 4 files changed, 1189 insertions(+), 32 deletions(-) > > I have re-started to review this change now, however as stated earlier > - the total number changes really doesn't make this easy to review. > > Until I am done, I have published a new cmdq_v9 branch via my mmc tree. Have you done any more testing?
