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Re: Pass 4 (non-)optimization speedup
- From: Josh Stone <jistone at redhat dot com>
- To: Mark Wielaard <mjw at redhat dot com>
- Cc: systemtap at sources dot redhat dot com
- Date: Tue, 14 Jul 2009 19:17:35 -0700
- Subject: Re: Pass 4 (non-)optimization speedup
- References: <1247337122.2708.24.camel@hermans.wildebeest.org>
On 07/11/2009 11:32 AM, Mark Wielaard wrote:
> The -O0 default speeds up some things a lot.
> $ stap -v -k -p4 -e 'probe syscall.* { log(argstr); }'
> Before: Pass 4: compiled C [...] in 7520usr/900sys/8415real ms.
> After: Pass 4: compiled C [...] in 4980usr/730sys/5782real ms.
By the way, -k will bypass ALL caching, including the saved autoconf
header. Generating that header is a few seconds in penalty that you
wouldn't normally hit when iterating on a script, since the autoconf is
cached independently of script contents.
It might be nice to split session.use_cache so that the tracepoint and
autoconf caches can be used even if the script-specific caches are not
used (due to -k or -m).
Josh