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Re: Meeting minutes 20060727
- From: Vara Prasad <prasadav at us dot ibm dot com>
- To: "Stone, Joshua I" <joshua dot i dot stone at intel dot com>
- Cc: jrs at us dot ibm dot com, "Frank Ch. Eigler" <fche at redhat dot com>, Masami Hiramatsu <masami dot hiramatsu dot pt at hitachi dot com>, systemtap at sources dot redhat dot com, Mathieu Desnoyers <mathieu dot desnoyers at polymtl dot ca>
- Date: Thu, 03 Aug 2006 17:22:46 -0700
- Subject: Re: Meeting minutes 20060727
- References: <C56DB814FAA30B418C75310AC4BB279D62E29D@scsmsx413.amr.corp.intel.com>
Stone, Joshua I wrote:
On Thursday, August 03, 2006 12:43 PM, Jose R. Santos wrote:
Frank Ch. Eigler wrote:
"Jose R. Santos" <firstname.lastname@example.org> writes:The goal here is to improve performance. Gui Jian has timed
[...] One of the things we are currently working on is to have anJosh Stone's kprobes-safe rendition gettimeofday has been in the
alternative to gettimeofday. [...]
systemtap runtime for some time now. Is that not sufficient for
_stp_gettimeofday_us() using LKET and it give a bigger overhead than
do_gettimeofday(). By doing this in user space we can obtain better
performance by avoiding disabling preemption or calling seqlock like
If you have suggestions for improving _stp_gettimeofday, I'm all ears.
I'm never of the mind that the existing code is the perfect solution.
But then, if you're doing something from userspace, I guess I don't
fully understand your usage model, or how that will be faster...
During one of the BOF's in OLS the discussion of do_gettimeofday()
overhead came, everyone agreed it is slow. Someone suggested that Linux
now has more efficient interface to get the timestamp, my notes seems to
lack details, does anyone remember what was the alternative suggestion.
I vaguely recollect that either real time guys or the high resolution
timer folks have introduced an interface which is platform dependent but
more efficient. If anyone can recollect details of this please post it.