Date: Sat, 12 Oct 2013 10:32:03 -0500 From: Pedro Giffuni <pfg@FreeBSD.org> To: Mark Johnston <markj@freebsd.org> Cc: dtrace@FreeBSD.org Subject: Re: Dtrace providers wanted list Message-ID: <52596B73.2050702@FreeBSD.org> In-Reply-To: <20131010042544.GB65451@raichu> References: <52546385.2050203@FreeBSD.org> <20131010042544.GB65451@raichu>
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On 09.10.2013 23:25, Mark Johnston wrote: > On Tue, Oct 08, 2013 at 02:56:53PM -0500, Pedro Giffuni wrote: >> Hello; >> >> Sometime ago I looked around the list of Oracle's DTrace providers. >> >> https://wikis.oracle.com/display/DTrace/Providers >> >> We absolutely want them and although extremely useful as it is, DTrace >> won't be complete until we have them all ;). For the time being we >> should probably focus on getting the really critical ones though. >> >> The first in the list that we don't have that I think is critical is >> mentioned in Brendan Gregg's FreeBSD specific blog post: >> >> http://dtrace.org/blogs/brendan/2013/09/25/the-use-method-freebsd-performance-checklist/ >> >> "Tracing paging is tricker until the vminfo provider is added; you could >> try tracing from swap_pager_putpages() and swap_pager_getpages(), but I >> didn’t see an easy way to walk back to a thread struct; another approach >> may be via vm_fault_hold(). Good luck. ..." I started looking at this but it is somewhat more work than expected: Solaris has a specific vminfo interface in sysinfo.h. It looks very handy for providing general vm statistics but our vm is different and I am not sure we want to go into implementing such interface. It depends on a VM guru, anyways. OTOH, I found the fsinfo provider: https://bitbucket.org/illumos/illumos-gate/commits/5b50c2dcfdf948c4e4f0b880eb76210067e7af7c Our VFS does have some similarity so this may be easier/doable, plus it may be needed by the scsi and ZFS providers. >> This is closely related to pmc(3) but obviously our implementation is >> completely different from the Solaris one. >> >> >> Well, just though I should share the above links in the hope of >> motivating more DTrace provider porting. At this time our base Dtrace >> port is pretty good but we have the chicken and egg problem where >> developers don't know how useful DTrace really is because there is no >> provider for their code. > I think it's also important to have more and better documentation of > existing providers. More providers are nice, but they're not as useful > when their existence is not widely known or it's not clear how they > might be used. > > I don't really like having links to an Oracle wiki page at least partly > because none of the FreeBSD ports of those providers are 100% compatible. > I've started writing man pages for the network providers; an example is > here: > > http://people.freebsd.org/~markj/dtrace/dtrace-ip.4.txt > > But I'm open to other forms of documentation as well. The Wiki would probably better while things settle. Pedro.
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