Date: Wed, 29 Jul 2009 13:39:17 -0700 From: Yuri <yuri@rawbw.com> To: Stanislav Sedov <stas@freebsd.org> Cc: freebsd-hackers@freebsd.org Subject: Re: How to profile the disk io performed through mmaps? Message-ID: <4A70B375.1050900@rawbw.com> In-Reply-To: <20090729124939.0082e1d6.stas@FreeBSD.org> References: <4A6F98F7.2080304@rawbw.com> <20090729124939.0082e1d6.stas@FreeBSD.org>
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Stanislav Sedov wrote: > Yes, it should be possible to monitor files written to via mmapped region > with EVFILT_VNODE kevents. Please note, however, that changes to mmapped > region may be propagated to the files not immediately depending on the > region attributes. > From kqueue(2) I don't see how to get details (offsets/sizes) of write/extend events on the file. When I ask filter EVFILT_VNODE to monitor events NOTE_EXTEND and NOTE_WRITE kevent returns when any of them occur and it even ors NOTE_EXTEND and NOTE_WRITE flags in the output kevent structure. It gives no further details. So my question is largely open: how to monitor actual reads/writes on the file? Yuri
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