Date: Thu, 5 May 2011 16:33:09 -0700 From: "David Christensen" <davidch@broadcom.com> To: "Artem Belevich" <art@freebsd.org> Cc: "freebsd-current@freebsd.org" <freebsd-current@freebsd.org> Subject: RE: Using Dtrace for Performance Evaluation Message-ID: <5D267A3F22FD854F8F48B3D2B523819360D799A517@IRVEXCHCCR01.corp.ad.broadcom.com> In-Reply-To: <BANLkTin0HxinK9e5w1VDsrse_L1xSEEW5g@mail.gmail.com> References: <5D267A3F22FD854F8F48B3D2B523819360D799A42B@IRVEXCHCCR01.corp.ad.broadcom.com> <BANLkTin0HxinK9e5w1VDsrse_L1xSEEW5g@mail.gmail.com>
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> > After building dtrace into the kernel and loading the dtraceall > > kernel module, when I load my bxe kernel module and run "dtrace -l" > > to list all supported probes I notice that many functions have an > > entry probe but no exit probe. =A0This effectively prevents me from > > calculating timestamps on "fbt:if_bxe::return" probes. =A0Why am I > > seeing this behavior? >=20 > Tail call optimization could do that to you: > http://en.wikipedia.org/wiki/Tail_call How to disable tail call optimization when building my driver? Dave
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