Date: Sat, 21 Nov 2015 22:29:37 -0800 From: "Simon J. Gerraty" <sjg@juniper.net> To: Mark Johnston <markj@freebsd.org> Cc: <freebsd-arch@freebsd.org>, <sjg@juniper.net> Subject: Re: zero-cost SDT probes Message-ID: <2753.1448173777@chaos> In-Reply-To: <20151122024542.GA44664@wkstn-mjohnston.west.isilon.com> References: <20151122024542.GA44664@wkstn-mjohnston.west.isilon.com>
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Mark Johnston <markj@freebsd.org> wrote: > For the past while I've been experimenting with various ways to > implement "zero-cost" SDT DTrace probes. Basically, at the moment an SDT > probe site expands to this: Would it be feasible to compile the probes into the kernel as active calls to a registrar function? That would eliminate all the complexity of finding PC's though you'd probably need to pass extra args to convey the point of the probe? It would hurt boot time a little too - each probe point would make a call to register itself (and get overwritten with nops as a reward) but very simple?
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