Re: STL Queue and multithreading

James Kanze <>
Thu, 11 Nov 2010 01:37:40 -0800 (PST)
On Nov 10, 10:26 pm, "Chris M. Thomasson" <> wrote:

"Juha Nieminen" <nos...@thanks.invalid> wrote in message


Goran Pusic <> wrote:

I would like to minimize the mutex usage

Minimize? Why? What performance numbers you have to back that?

It's a well-known fact that software mutexes are extremely
slow and can seriously impact performance in situations
where the data container needs to be accessed a very large
amount of times very fast.

FWIW, mutex lock/unlock usually costs 2 atomic RMW operations
and 2 memory barriers, one of which may very well be
a #StoreLoad. All of that can be fairly expensive...

Compared to what? (And why two atomic operations? I think
I could implement a Mutex lock with a single CAS.)

The memory barriers are expensive compared to any single
instruction, but in most programs, you shouldn't require the
lock very often. And they aren't expensive, or even
significant, compared to any other important calculations.

James Kanze

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