Date: Thu, 26 Nov 2015 09:30:51 +0200 From: Andriy Gapon <avg@FreeBSD.org> To: Mark Johnston <markj@FreeBSD.org>, Konstantin Belousov <kostikbel@gmail.com> Cc: freebsd-arch@FreeBSD.org Subject: Re: zero-cost SDT probes Message-ID: <5656B52B.90203@FreeBSD.org> In-Reply-To: <20151125232524.GB67865@wkstn-mjohnston.west.isilon.com> References: <20151122024542.GA44664@wkstn-mjohnston.west.isilon.com> <20151123113511.GX58629@kib.kiev.ua> <20151125001136.GB70878@wkstn-mjohnston.west.isilon.com> <20151125131533.GB3448@kib.kiev.ua> <20151125232524.GB67865@wkstn-mjohnston.west.isilon.com>
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On 26/11/2015 01:25, Mark Johnston wrote: > On Wed, Nov 25, 2015 at 03:15:33PM +0200, Konstantin Belousov wrote: >> Several variations of the approach allow to control each probe site >> individually, while still avoiding jumps and reducing the cache consumption. >> And, of course, the biggest advantage is avoiding the need to change the >> text at runtime. [snip] > I see. I think this could be made to work, but there's still the > complication of passing arguments to the probe. Copying them into some > block in curthread is one way to do this, but it seems more expensive > than the standard calling convention on amd64 at least. Besides, the FBT probes are not going anywhere and they require the run-time text modification. -- Andriy Gapon
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