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Re: [Qemu-devel] [RFC] [PATCHv10 19/31] aio / timers: Use all timerlists


From: Alex Bligh
Subject: Re: [Qemu-devel] [RFC] [PATCHv10 19/31] aio / timers: Use all timerlists in icount warp calculations
Date: Thu, 15 Aug 2013 19:31:16 +0100

On 15 Aug 2013, at 13:37, Alex Bligh wrote:

>> I see no value in a spurious wakeup if no deadline was set, but it's
>> harmless.
>> 
>> As for overflow, I don't really understand how INT32_MAX prevents
>> overflow.  If the base timer value we're adding to is already huge then
>> INT32_MAX could still overflow it.
> 
> This is my understanding. I don't think we need to worry about overflowing
> int64_t.

I think this /might/ refer to the similar bit of nastiness in tcg_cpu_exec,
where the parameter gets sent off to qemu_icount_round. It isn't evident
this has been built with signed integers in mind. I'm hesitant to fix one
without the other.

Given no one has been jumping up and down saying "I know how icount works
and you should just delete these", I think I'll leave them in for v11,
as the result is every two and a half seconds there's an extra wake
up when using icount, as far as I can tell.

If the jumping up and down person appears, he/she can delete a few lines.

So v11 is currently planned just to fix Jan's include file issue.

-- 
Alex Bligh







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