Date: Fri, 10 Jul 2009 15:27:15 +0300 From: Andriy Gapon <avg@freebsd.org> To: Andrew Brampton <brampton+freebsd@gmail.com> Cc: freebsd-current@freebsd.org Subject: Re: dtrace users opinion solicited (timestamps) Message-ID: <4A5733A3.20409@freebsd.org> In-Reply-To: <d41814900907091502gbcd7e47h6982dbcf2e837963@mail.gmail.com> References: <4A562960.3010801@freebsd.org> <d41814900907091502gbcd7e47h6982dbcf2e837963@mail.gmail.com>
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on 10/07/2009 01:02 Andrew Brampton said the following: > According to wikipedia newer Intel processors have a constant rate TSC > whos freq does not change. If this features is available on most > processors today, then I am happy to stick with option 1. > > Another problem with this is that on a multicore machine each core may > have different TSC values. Has anyone thought how to address this > issue? Could we calculate the offset of each core from core0, and then > ensure the offset is applied to the tsc value when it is needed? Yes. The actual code accounts for inter-CPU/core TSC skew. -- Andriy Gapon
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