os/bluestore: sloppy reshard boundaries to avoid spanning blobs #11263
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Make the extent map shard target size sloppy so that we can try to avoid sharding boundaries that create spanning blobs. Signed-off-by: Sage Weil <sage@redhat.com>
somnathr
reviewed
Sep 29, 2016
| @@ -1521,7 +1523,10 @@ void BlueStore::ExtentMap::reshard(Onode *o) | |||
| dout(20) << __func__ << " old shard end 0x" << std::hex << shard_end | |||
| << std::dec << dendl; | |||
| } | |||
| if (estimate && estimate + extent_avg > target) { | |||
| // disfavor shard boundaries that span a blob | |||
| bool would_span = (ep->logical_offset < max_blob_end) || ep->blob_offset; | |||
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@liewegas I don't understand why it would span if ep->blob_offset is non zero ?
Could you also help me understand what is the difference between logical_offset and blob_offset within an extent ?
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blob_offset means this Extent points to the interior of the blob, not the left-hand side. That means that if we put a shard boundary starting at ep->logical_offset, the blob would span the boundary.
This was referenced Jun 21, 2023
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Make the extent map shard target size sloppy so that we can try to avoid
sharding boundaries that create spanning blobs.
Signed-off-by: Sage Weil sage@redhat.com