Differential D14988
Pat the watchdog less while producing a coredump Authored by jtl on Apr 6 2018, 3:03 PM. Tags None Referenced Files
Details Prior to this change, we patted the watchdog approximately once per 4KB page of memory. After this change, we pat the watchdog approximately once per 128MB of memory. On a sample machine, this translated to patting the watchdog approximately every 5.4 seconds, which "seems reasonable". We can choose a different value in the future, if warranted. This has extensive field experience. It is a performance improvement, and has not caused any known problems.
Diff Detail
Event TimelineComment Actions How much of a difference does this make in write speed for the dumps? Do we have numbers on it? Comment Actions No, we don't have numbers. However, @gallatin said it was a "measurable speedup" when he applied it. Comment Actions OK. so at least 10% faster :) I've looked at the code, and apart from some wonky inverted logic that wasn't clear (but was correct), it looks good to me. It's a shame we can't use the 'counter' stuff to do the touching since that would make the code simpler, but is every 16MB. |