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| H A D | qsp.c | ac8c7748 Mon Sep 10 18:27:44 CDT 2018 Emilio G. Cota <cota@braap.org> qsp: use atomic64 accessors
With the seqlock, we either have to use atomics to remain
within defined behaviour (and note that 64-bit atomics aren't
always guaranteed to compile, irrespective of __nocheck), or
drop the atomics and be in undefined behaviour territory.
Fix it by dropping the seqlock and using atomic64 accessors.
This will limit scalability when !CONFIG_ATOMIC64, but those
machines (1) don't have many users and (2) are unlikely to
have many cores.
- With CONFIG_ATOMIC64:
$ tests/atomic_add-bench -n 1 -m -p
Throughput: 13.00 Mops/s
- Forcing !CONFIG_ATOMIC64:
$ tests/atomic_add-bench -n 1 -m -p
Throughput: 10.89 Mops/s
Signed-off-by: Emilio G. Cota <cota@braap.org>
Message-Id: <20180910232752.31565-5-cota@braap.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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