Messages in this thread |  | | | From | Linus Torvalds <> | | Date | Thu, 11 Nov 2010 11:37:28 -0800 | | Subject | Re: [RFC/RFT PATCH v3] sched: automated per tty task groups |
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On Thu, Nov 11, 2010 at 11:08 AM, Mike Galbraith <efault@gmx.de> wrote: > >> - the reason I suggested the signal struct was really that I thought >> it would avoid extra (unnecessary) cost in thread creation/teardown. >> >> Maybe I should have made that clear, but this seems to >> unnecessarily do the whole atomic_inc/dec for each thread. That seems >> a bit sad. >> >> That said, if not having to dereference ->signal simplifies the >> scheduler interaction, I guess the extra atomic ref at thread >> creation/deletion is fine. So I don't think this is wrong, it's just >> something I wanted to bring up. > > Ah, ok. Anything that cuts overhead is worth doing.
Well, it cuts both ways. Maybe your approach is simpler and avoids overhead at scheduling time. And "tsk->signal" may not be reliable due to races with exit etc, so it may well be that going through the signal struct could end up being a source of nasty races. I didn't look whether the scheduler already derefenced ->signal for some other reason, for example.
So your patch may well have done the exact right thing.
Linus -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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