Messages in this thread | | | Date | Mon, 27 Apr 2015 15:14:49 -0700 | Subject | Re: [GIT PULL] kdbus for 4.1-rc1 | From | Linus Torvalds <> |
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On Mon, Apr 27, 2015 at 3:00 PM, Linus Torvalds <torvalds@linux-foundation.org> wrote: > > IOW, all the people who say that it's about avoiding context switches > are probably just full of shit. It's not about context switches, it's > about bad user-level code.
Just to make sure, I did a system-wide profile (so that you can actually see the overhead of context switching better), and that didn't change the picture.
The scheduler overhead *might* be 1% or so.
So really. The people who talk about how kdbus improves performance are just full of sh*t. Yes, it improves things, but the improvement seems to be 100% "incidental", in that it avoids a few trips down the user-space problems.
The real problems seem to be in dbus memory management (suggestion: keep a small per-thread cache of those message allocations) and to a smaller degree in the crazy utf8 validation (why the f*ck does it do that anyway?), with some locking problems thrown in for good measure.
Linus
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