Date: Wed, 23 Jan 2013 11:31:43 -0500 From: John Baldwin <jhb@freebsd.org> To: Mikolaj Golub <trociny@freebsd.org> Cc: Stanislav Sedov <stas@freebsd.org>, freebsd-hackers@freebsd.org, Robert Watson <rwatson@freebsd.org> Subject: Re: libprocstat(3): retrieve process command line args and environment Message-ID: <201301231131.43972.jhb@freebsd.org> In-Reply-To: <20130123072459.GA48402@gmail.com> References: <20130119151253.GB88025@gmail.com> <9679EEE4-BE52-493E-9188-CAECEE5E63D3@freebsd.org> <20130123072459.GA48402@gmail.com>
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On Wednesday, January 23, 2013 2:25:00 am Mikolaj Golub wrote: > On Tue, Jan 22, 2013 at 02:17:39PM -0800, Stanislav Sedov wrote: > > > > On Jan 22, 2013, at 1:48 PM, John Baldwin <jhb@freebsd.org> wrote: > > > > > > Well, you could make procstat open a kvm handle in both cases (open a "live" > > > handle in the procstat_open_sysctl() case). It just seems rather silly to be > > > duplicating code in the two interfaces. > > In this particular case I prefer code duplication to opening a kvm > handle in procstat_open_sysctl(), as it looks a bit confusing. But I > can do this way if the agreement is reached. > > > > More a question for Robert: does > > > libprocstat intentionally duplicate the code in libkvm for other things as > > > well in the live case? (Like fetching the list of processes?) > > > > > It does not actually has a duplicate code, the code for fetching the list of > > processes via sysctl is different from the KVM case. The open file descriptors > > processing is different as well. Because libprocstat implements almost the > > same functionality both for sysctl and mvm backends, it can be used to analyze > > both the live system and the kernel crash dumps. The code Mikolaj proposed > > only implements the sysctl backend currently, so it does not seem to have > > any relation to KVM, so it will be a bit weird to make it open a KVM handle > > though it does not use it. > > IMHO, after adding procstat_getargv and procstat_getargv, the usage of > kvm_getargv() and kvm_getenvv() (at least in the new code) may be > deprecated. As this is stated in the man page, BUGS section, "these > routines do not belong in the kvm interface". I suppose they are part > of libkvm because there was no a better place for them. procstat(1) > prefers direct sysctl to them (so, again, code duplication, which I am > going to remove adding procstat_getargv/envv). Hmm, are you going to rewrite ps(1) to use libprocstat? Or rather, is that a goal someday? That is one current consumer of kvm_getargv/envv. That might be fine if we want to make more tools use libprocstat instead of using libkvm directly. -- John Baldwin
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