Date: Mon, 16 Oct 2017 17:19:46 -0600 From: Ian Lepore <ian@freebsd.org> To: Mateusz Guzik <mjguzik@gmail.com>, Rick Macklem <rmacklem@uoguelph.ca> Cc: "freebsd-current@freebsd.org" <freebsd-current@freebsd.org>, "fabian.freyer@physik.tu-berlin.de" <fabian.freyer@physik.tu-berlin.de> Subject: Re: pfind_locked(pid) fails when in a jail? Message-ID: <1508195986.74236.6.camel@freebsd.org> In-Reply-To: <CAGudoHEvDk0mKCmK59sPM7j-Mt279rLZwTwVazX5ktX=7wD-9Q@mail.gmail.com> References: <YTOPR0101MB2172A4421C7B012A503230D5DD4F0@YTOPR0101MB2172.CANPRD01.PROD.OUTLOOK.COM> <CAGudoHEvDk0mKCmK59sPM7j-Mt279rLZwTwVazX5ktX=7wD-9Q@mail.gmail.com>
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On Tue, 2017-10-17 at 00:38 +0200, Mateusz Guzik wrote: > On Tue, Oct 17, 2017 at 12:24 AM, Rick Macklem <rmacklem@uoguelph.ca> wrote: > > > > > Hi, > > > > A problem w.r.t. the NFSv4 client's renew thread (nfscl) running up a lot > > of CPU > > when the NFSv4 mount is in a jail has been reported to the freebsd-stable@ > > mailing list. > > > > I know nothing about jails, but when looking at the code, the most obvious > > cause of this would be "pfind_locked(pid)" failing to find a process. > > - Will a jail affect how pfind_locked() behaves? > > - If the answer is "yes", then I need to know how to either... > > 1 - Make pfind_locked() work the same as when no jail exists. > > OR > > 2 - A way for the Renew thread can determine that a jail will affect > > pfind_locked() > > behaviour, so it can avoid this problem. > > #1 is preferred, since #2 may not be 100% correct, although #2 would allow > > the > > code to behave well for most cases. (The exception is a case where a file > > remains > > open for a long period of time, with different processes doing byte range > > locks on > > the file.) > > > pfind* does not do any filtering. > > The real question though is why are you calling it in the first place. The > calls > I grepped in nfscl_procdoesntexist are highly suspicious - there is no > guarantee > the process you found here is the same you had at the time you were saving > the pid. > > There is no usable process exit notification right now, but it can be added > if necessary. > Does that mean there is something wrong with the existing eventhandler notifications related to proc fork/exec/exit? -- Ian
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