lib/checkout: Optimize checkout by avoiding OstreeRepoFile recusion #848
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Since we now have a cleaner separation of "toplevel checkout prep" versus "recursive checkout", handle the special case of checking out a single file at first rather than later. Prep for future work in optimizing this function more.
Looking at `perf record ostree checkout`, some things stand out; e.g.: ``` + 27.63% 0.07% ostree libgio-2.0.so.0.5000.3 [.] g_file_enumerator_iterate + 22.74% 0.28% ostree libostree-1.so.1.0.0 [.] ostree_repo_file_tree_query_child + 13.74% 0.08% ostree libostree-1.so.1.0.0 [.] ot_variant_bsearch_str ``` The GIO abstractions are already fairly heavyweight, and `OstreeRepoFile` mallocs a lot too. Make things more efficient here by dropping the GIO bits for reading ostree data - we just read from the variants directly and iterate over them. The end result here is that according to perf we go from ~40% of our time in the kernel to ~70%, and things like `g_file_enumerator_iterate()` drop entirely out of the hot set.
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Looks good! @rh-atomic-bot r+ a4fc72e |
rh-atomic-bot
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May 11, 2017
Looking at `perf record ostree checkout`, some things stand out; e.g.: ``` + 27.63% 0.07% ostree libgio-2.0.so.0.5000.3 [.] g_file_enumerator_iterate + 22.74% 0.28% ostree libostree-1.so.1.0.0 [.] ostree_repo_file_tree_query_child + 13.74% 0.08% ostree libostree-1.so.1.0.0 [.] ot_variant_bsearch_str ``` The GIO abstractions are already fairly heavyweight, and `OstreeRepoFile` mallocs a lot too. Make things more efficient here by dropping the GIO bits for reading ostree data - we just read from the variants directly and iterate over them. The end result here is that according to perf we go from ~40% of our time in the kernel to ~70%, and things like `g_file_enumerator_iterate()` drop entirely out of the hot set. Closes: #848 Approved by: jlebon
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☀️ Test successful - status-atomicjenkins |
cgwalters
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May 12, 2017
This is what caused the merge of coreos/rpm-ostree#652 to blow up, since ostreedev#848 landed right before we tried to merge it. When I was writing that PR I remember having an uncertain feeling since we were doing a `mkdirat` above, but at the time I thought we'd have test suite coverage...turns out we didn't. For backwards compatibility, we need to continue to do a `mkdirat` here of the parent. However...I can't think of a reason anyone would *want* that behavior. Hence, let's add a special trick - if the destination name is `.`, we skip `mkdirat()`. That way rpm-ostree for example can open a dfd for `/etc` and avoid the `mkdir`. Fold the subpath tests into `test-basic.sh` since it's not worth a separate file. Add a test case for checking out a file.
rh-atomic-bot
pushed a commit
that referenced
this pull request
May 12, 2017
This is what caused the merge of coreos/rpm-ostree#652 to blow up, since #848 landed right before we tried to merge it. When I was writing that PR I remember having an uncertain feeling since we were doing a `mkdirat` above, but at the time I thought we'd have test suite coverage...turns out we didn't. For backwards compatibility, we need to continue to do a `mkdirat` here of the parent. However...I can't think of a reason anyone would *want* that behavior. Hence, let's add a special trick - if the destination name is `.`, we skip `mkdirat()`. That way rpm-ostree for example can open a dfd for `/etc` and avoid the `mkdir`. Fold the subpath tests into `test-basic.sh` since it's not worth a separate file. Add a test case for checking out a file. Closes: #854 Approved by: jlebon
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Looking at
perf record ostree checkout, some things stand out; e.g.:The GIO abstractions are already fairly heavyweight, and
OstreeRepoFilemallocsa lot too.
Make things more efficient here by dropping the GIO bits for reading ostree data -
we just read from the variants directly and iterate over them. The end result
here is that according to perf we go from ~40% of our time in the kernel to
~70%, and things like
g_file_enumerator_iterate()drop entirely out of thehot set.