nptl status?

nptl status?

[Stuart Jansen]

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I read, I think on the Xen Web site, that Xen doesn't support NPTL yet.
Digging through the Xen mailing list a few days ago, I saw a message
that implied it is working now. What is the current status of NPTL in
Xen? Out of curiosity, if it is not yet supported, what would be needed
to support it? How hard would it be for a person with zero Xen
experience to ramp up and work on adding NPTL support?

(Sorry I can't be more specific, I spent my Thanksgiving processing >
3000 emails, and doing alot of other other reading.)

-- 
Stuart Jansen <sjansen@gurulabs.com>
Guru Labs, L.C.

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Re: nptl status?

[Ian Pratt]

> I read, I think on the Xen Web site, that Xen doesn't support NPTL yet.
> Digging through the Xen mailing list a few days ago, I saw a message
> that implied it is working now. What is the current status of NPTL in
> Xen? Out of curiosity, if it is not yet supported, what would be needed
> to support it? How hard would it be for a person with zero Xen
> experience to ramp up and work on adding NPTL support?

NPTL is supported, but we're forced to take traps for almost
every attempt to access thread local storage, which is slow (I
think Rik said 12-15% on a kernel compile).

The only way to improve on this would be to have our own very
slightly modified version of libc that could be installed to
restore full performance. We're hoping to look into this at some
point.

Disabling NPTL works for most people.

Ian



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