Re: trace-cmd library: Add ZSTD support.

[Sebastian Andrzej Siewior <sebastian@breakpoint.cc>]

On 2022-02-20 12:11:43 [-0500], Steven Rostedt wrote:
> On Sun, 20 Feb 2022 00:01:50 +0100
> Sebastian Andrzej Siewior <sebastian@breakpoint.cc> wrote:
> 
> > Steven mentioned that trace-cmd recently gained compression support. I
> > suggest to remove zlib since there is no real benefit to use this
> > compression algorithm.
> 
> One benefit is to just have a test case for multiple versions. And who
> knows, if it is an easy implementation, perhaps there's something that
> needs it in a very limited embedded environment? Does it really hurt
> keeping it, even though it may never be used?

Especially in embedded environment I would prefer zstd over zlib because
it performance. These days, if you can allow to compile trace-cmd you
should be able to include zstd, too. One downside is probably that the
zstd library is larger than libz.

> > It might make sense to use zstd while dumping the per-CPU data files
> > disks before the trace.dat is written. It probably makes sense to use
> > zstd by default instead of storing the .dat file uncompressed.
> 
> I have a patch that does the compression by default. I'm holding off
> pushing it until I finished my testing of the compressed versions.

Awesome. I don't know how you make trace.dat in the end but I saw that
there is one trace file per CPU first. Would it make sense to compress
these before they are written to disk?

> Thanks Sebastian for this update!

You are welcome.

> -- Steve

Sebastian