pull: Add OSTREE_PULL_MAX_OUTSTANDING_WRITES env var #2147
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Any preliminary results on how effective this is? Feels like the better thing to throttle is size of outstanding objects instead of number of objects, though that's a bigger patch. If it unblocks openshift/machine-config-operator#1897 though, WFM! (Could probably make it a repo config knob instead/in addition?). |
We need to expose more control over how fast we write to disk in order to allow OS vendors to more finely tune latency vs throughput for OS updates. See openshift/machine-config-operator#1897 This `OSTREE_PULL_MAX_OUTSTANDING_WRITES` is a crude hack I'm using for testing; need to also expose this via API, document it etc. Second, add a `per-object-fsync` option which goes back to invoking `fsync()` on each object just after writing it. Combined, these two ensure natural "backpressure" against trying to fsync a huge amount of data all at once, which I believe is what is leading to the huge etcd fsync latency.
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Moved this to #2152 |
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We need to expose more control over how fast we write to disk
in order to allow OS vendors to more finely tune latency vs
throughput for OS updates.
See openshift/machine-config-operator#1897
This is a crude hack I'm using for testing; need to also
expose this via API, document it etc.