On 22/09/2023 21:12, Johannes Berg wrote:
On Fri, 2023-09-22 at 21:08 +0100, Anton Ivanov wrote:
On 22/09/2023 20:41, Johannes Berg wrote:
On Fri, 2023-09-22 at 14:41 +0100, Anton Ivanov wrote:
It is nearly twice slower than the current approach on a find /usr -type f -exec
cat {} > /dev/null \;
Btw, I cannot reproduce that at all - seems about the same in my tests?
Is there anything special in your setup?
Or maybe it's because I'm using hostfs? But not sure why that would
matter.
I am using a ubd with ext4 sitting on an nfs server. The host, however,
has more than enough memory to cache all of it, so it is pretty much
like reading off a ramdisk as it is fully cached.
It is quite clear in that case.
Did you have your preempt patch applied also, btw? Because I was working
off that now.
But even with PREEMPT turned off, I see basically no difference in such
One more thing. Is your find "real" /bin/find or busybox.
Real find will exec() /bin/cat
Busybox find will shortcut internally to the code of its cat applet. As
a result it is much faster and there is no exec overhead.
a benchmark. I was running only over /usr/bin/ because otherwise it's
just too much time on my system overall, but there's basically no
difference in the 4x4 matrix of
- preempt off / preempt voluntary
- with / without my patch
johannes
--
Anton R. Ivanov
Cambridgegreys Limited. Registered in England. Company Number 10273661
https://www.cambridgegreys.com/
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