> On 24 May 2017, at 17:25, Daniel P. Berrange <berra...@redhat.com> wrote: > > On Wed, May 24, 2017 at 05:10:03PM +0100, Felipe Franciosi wrote: >> The commit message from 070afca25 suggests that dirty_rate_high_cnt >> should be used more aggressively to start throttling after two >> iterations instead of four. The code, however, only changes the auto >> convergence behaviour to throttle after three iterations. This makes the >> behaviour more aggressive by kicking off throttling after two iterations >> as originally intended. > > This description looks suspect vs the code. You say it is changing > from "after four" to "after two", but you are merely switching a > post-increment to a pre-increment which can only reduce the boundary > condition by 1, not 2. So either you mean to write > > "after two iterations instead of three" > > or > > "after three iterations intead of four"
Hi Daniel, Thanks for the quick feedback. Let me clarify what I meant. If there's still confusion I'll update the commit message to reflect it better. Pre-070afca25: throttling kicked in after four iterations. Post-070afca25: throttling kicked in after three iterations (but Jason wrote he meant to start throttling after two). This patch: throttles kicks in after two iterations (so Jason's code, minus one). Perhaps where I said "The code, however," I could say "Commit 070afca25, however,". Let me know. Thanks, Felipe > >> >> Signed-off-by: Felipe Franciosi <fel...@nutanix.com> >> --- >> migration/ram.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/migration/ram.c b/migration/ram.c >> index 1a3d9e6..26e03a5 100644 >> --- a/migration/ram.c >> +++ b/migration/ram.c >> @@ -708,7 +708,7 @@ static void migration_bitmap_sync(RAMState *rs) >> >> if ((rs->num_dirty_pages_period * TARGET_PAGE_SIZE > >> (bytes_xfer_now - rs->bytes_xfer_prev) / 2) && >> - (rs->dirty_rate_high_cnt++ >= 2)) { >> + (++rs->dirty_rate_high_cnt >= 2)) { >> trace_migration_throttle(); >> rs->dirty_rate_high_cnt = 0; >> mig_throttle_guest_down(); >> -- >> 1.9.5 >> >> > > Regards, > Daniel > -- > |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| > |: https://libvirt.org -o- https://fstop138.berrange.com :| > |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|