linux-kernel - Re: [PATCH v3 00/35] Memory allocation profiling

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Message-ID: <Zc0f7u5yCq-Iwh3A@google.com>
Date: Wed, 14 Feb 2024 20:17:50 +0000
From: Yosry Ahmed <yosryahmed@...gle.com>
To: Suren Baghdasaryan <surenb@...gle.com>
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Subject: Re: [PATCH v3 00/35] Memory allocation profiling

> > > Performance overhead:
> > > To evaluate performance we implemented an in-kernel test executing
> > > multiple get_free_page/free_page and kmalloc/kfree calls with allocation
> > > sizes growing from 8 to 240 bytes with CPU frequency set to max and CPU
> > > affinity set to a specific CPU to minimize the noise. Below are results
> > > from running the test on Ubuntu 22.04.2 LTS with 6.8.0-rc1 kernel on
> > > 56 core Intel Xeon:
> > >
> > >                         kmalloc                 pgalloc
> > > (1 baseline)            6.764s                  16.902s
> > > (2 default disabled)    6.793s (+0.43%)         17.007s (+0.62%)
> > > (3 default enabled)     7.197s (+6.40%)         23.666s (+40.02%)
> > > (4 runtime enabled)     7.405s (+9.48%)         23.901s (+41.41%)
> > > (5 memcg)               13.388s (+97.94%)       48.460s (+186.71%)
> 
> (6 default disabled+memcg)    13.332s (+97.10%)         48.105s (+184.61%)
> (7 default enabled+memcg)     13.446s (+98.78%)       54.963s (+225.18%)

I think these numbers are very interesting for folks that already use
memcg. Specifically, the difference between 6 & 7, which seems to be
~0.85% and ~14.25%. IIUC, this means that the extra overhead is
relatively much lower if someone is already using memcgs.

> 
> (6) shows a bit better performance than (5) but it's probably noise. I
> would expect them to be roughly the same. Hope this helps.
> 
> > >
> >
> >