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Re: [Qemu-arm] [PATCH 0/2] linux-user: Change mmap_lock to rwlock
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From: |
Richard Henderson |
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Subject: |
Re: [Qemu-arm] [PATCH 0/2] linux-user: Change mmap_lock to rwlock |
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Date: |
Sat, 23 Jun 2018 08:25:52 -0700 |
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User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.8.0 |
On 06/22/2018 02:12 PM, Emilio G. Cota wrote:
> I'm curious to see how much perf could be gained. It seems that the hold
> times in SVE code for readers might not be very large, which
> then wouldn't let us amortize the atomic inc of the read lock
> (IOW, we might not see much of a difference compared to a regular
> mutex).
In theory, the uncontended case for rwlocks is the same as a mutex.
> Are you using any benchmark that shows any perf difference?
Not so far. Glibc has some microbenchmarks for strings, which I will try next
week, but they are not multi-threaded. Maybe just run 4 threads of those
benchmark?
r~