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SubjectRe: Thread implementations...

On Sat, 20 Jun 1998, David S. Miller wrote:

> With pthreads it achieves 811 req/s.
> With user threads it achieves 1024.40 req/s.
>
> The machine is a single cpu ppro 200 with 128Mb of RAM running 2.1.104.
>
> If you have the opportunity, perform the same benchmark on an
> architecture that implements context pids in the TLB. The entire TLB
> is for all intents and purposes, flushed entirely of all userland
> translations for even thread context switches.

on x86 it is not flushed across thread-thread switches ... and on a PPro,
parts of the TLB are tagged as 'global' (kernel pages obviously), which
keeps the TLB-lossage even across non-shared-VM threads small. (zb->apache
and apache->zb switches in this case).

one thing i noticed about LinuxThreads, the most 'out of balance' basic
pthreads operation in pthread_create(). Does NSPR create a pre-allocated
pool of threads? (or some kind of adaptive pool?) If it's creating threads
heavily (say per-request), then thats bad, at least with the current
LinuxThreads implementation. We have a 1:5 gap between the latency of
clone() and pthread_create() there...

-- mingo


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