9922f33...
by
Benjamin Marzinski via lttng-dev <email address hidden>
fix: handle EINTR correctly in get_cpu_mask_from_sysfs
If the read() in get_cpu_mask_from_sysfs() fails with EINTR, the code is
supposed to retry, but the while loop condition has (bytes_read > 0),
which is false when read() fails with EINTR. The result is that the code
exits the loop, having only read part of the string.
Use (bytes_read != 0) in the while loop condition instead, since the
(bytes_read < 0) case is already handled in the loop.
When liburcu is configured to _not_ use atomic builtins, the
implementation of atomic operations is done using inline assembler for
each architecture.
Because we control the emitted assembler, we know whether specific
operations (e.g. lock; cmpxchg) already have an implicit memory barrier.
In those cases, emitting an explicit cmm_smp_mb() before/after the
operation is redundant and hurts performance.
ac73525...
by
Xenofon Foukas <email address hidden>
Add support for custom memory allocators for rculfhash
The current implementation of rculfhash relies on calloc()
to allocate memory for its buckets. This can in some cases
lead to latency spikes when accessing the hash table, which
can be avoided by using an optimized custom memory allocator.
However, there is currently no way of replacing the default
allocator with a custom one.
This commit allows custom allocators to be used during the
table initialization. The default behavior of the hash table
remains unaffected, by using the stdlib calloc() and free(),
if no custom allocator is given.
Older versions of GNU as do not support mftbl. The issue affects Darwin
PowerPC, as well as some older versions of NetBSD and Linux. Since mftb
is equivalent and universally understood, just use that.
