forked from luck/tmp_suning_uos_patched
6f91bc5fda
This patch introduces a fast path in ext4_ext_convert_to_initialized() for the case when the conversion can be performed by transferring the newly initialized blocks from the uninitialized extent into an adjacent initialized extent. Doing so removes the expensive invocations of memmove() which occur during extent insertion and the subsequent merge. In practice this should be the common case for clients performing append writes into files pre-allocated via fallocate(FALLOC_FL_KEEP_SIZE). In such a workload performed via direct IO and when using a suboptimal implementation of memmove() (x86_64 prior to the 2.6.39 rewrite), this patch reduces kernel CPU consumption by 32%. Two new trace points are added to ext4_ext_convert_to_initialized() to offer visibility into its operations. No exit trace point has been added due to the multiplicity of return points. This can be revisited once the upstream cleanup is backported. Signed-off-by: Eric Gouriou <egouriou@google.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> |
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| .. | ||
| events | ||
| define_trace.h | ||
| ftrace.h | ||
| syscall.h | ||