ping; I won't respin for patchew until this gets looked over again, sorry :)
On 01/19/2018 03:58 PM, John Snow wrote: > mirror_throttle attempts to make sure we yield every so often when we're > doing operations that may not otherwise be as cooperative as we'd like. > > This pattern is useful to other jobs like commit as well; if commit > continuously decides not to copy data (and calculates delay_ns to be 0), > we'll frequently and aggressively yield, only to be rescheduled immediately. > > This causes those "WARNING: I/O thread spun for 1000 iterations" > warnings that everyone loves so much. > > Split out the mirror_throttle function to become a new internal > BlockJob API function, block_job_throttle; then use it for all > the other jobs in their runtime loops. > > I decided to use it in stream and backup as well, so that regardless of if the > loop structure has the chance to be greedy or not (I did not audit this), the > BlockJob has some kind of failsafe that will occasionally perform a 0ns sleep > every SLICE_TIME. > > v2: > - Fixed spacing consistency (Paolo) > - Renamed last_yield_ns to last_enter_ns (Stefan) > - Renamed block_job_throttle to block_job_relax (Stefan) > - Removed external usages of block_job_pause_point and > block_job_sleep_ns (Paolo) > - Further cut down block/backup code to use block_job_relax > > ________________________________________________________________________________ > > For convenience, this branch is available at: > https://github.com/jnsnow/qemu.git branch block-job-yield > https://github.com/jnsnow/qemu/tree/block-job-yield > > This version is tagged block-job-yield-v2: > https://github.com/jnsnow/qemu/releases/tag/block-job-yield-v2 > > John Snow (13): > blockjob: record time of last entrance > blockjob: consolidate SLICE_TIME definition > blockjob: create block_job_relax > blockjob: allow block_job_throttle to take delay_ns > block/commit: use block_job_relax > block/stream: use block_job_relax > block/backup: use block_job_relax > allow block_job_relax to return -ECANCELED > block/backup: remove yield_and_check > block/mirror: condense cancellation and relax calls > block/mirror: remove block_job_sleep_ns calls > blockjob: privatize block_job_sleep_ns > blockjob: remove block_job_pause_point from interface > > block/backup.c | 27 ++++++----------------- > block/commit.c | 4 +--- > block/mirror.c | 52 > +++++++++++++++----------------------------- > block/stream.c | 4 +--- > block/trace-events | 2 +- > blockjob.c | 51 ++++++++++++++++++++++++++++++++++++------- > include/block/blockjob.h | 5 +++++ > include/block/blockjob_int.h | 37 +++++++++++++++---------------- > tests/test-bdrv-drain.c | 2 +- > tests/test-blockjob-txn.c | 2 +- > 10 files changed, 94 insertions(+), 92 deletions(-) >
