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(-)
>