Date: Sat, 23 Dec 2000 06:34:13 -0800 From: Cy Schubert - ITSD Open Systems Group <Cy.Schubert@uumail.gov.bc.ca> To: cjclark@alum.mit.edu Cc: Mikhail Teterin <mi@aldan.algebra.com>, Cy Schubert - ITSD Open Systems Group <Cy.Schubert@uumail.gov.bc.ca>, stable@FreeBSD.ORG Subject: Re: an unkillable process (again) Message-ID: <200012231434.eBNEYoc09416@cwsys.cwsent.com> In-Reply-To: Your message of "Sat, 23 Dec 2000 00:12:23 PST." <20001223001223.M96105@149.211.6.64.reflexcom.com>
next in thread | previous in thread | raw e-mail | index | archive | help
In message <20001223001223.M96105@149.211.6.64.reflexcom.com>, "Crist J. Clark" writes: > On Fri, Dec 22, 2000 at 12:57:13PM -0500, Mikhail Teterin wrote: > > Cy Schubert - ITSD Open Systems Group once stated: > > > > =In message <200012202226.eBKMQf100632@misha.privatelabs.com>, Mikhail > > =Teterin writes: > > => Here it is: > > => > > => 425 mi -18 0 45308K 144K swwrt 4:25 0.10% 0.10% communi > cator > > => -l > > => > > => For some bizarre reasons of its own, Netscape went into swap-writing > > => binge. Why did it make it immune to ``kill -9''? > > = > > =Then it appears that swwrt has a higher priority than kill has, which > > =it should have. > > > > Rather confusing... kill -9 does not deliver any signals to the process. > > It is there to kill. Shouldn't it have the higher priority? > > It is not a "priority" issue. The process is in the midst of an > operation that cannot be interupted. For some reason, that operation > is hanging up. I believe 'swwrt' is writing to swap? I/O calls are the > most frequent uninteruptable calls that get hung. Actually it is a "priority issue". Read Design and Implementation of the 4.4BSD Operating System pp 83-85, and pp 89: To prevent a sleeping process, e.g. one waiting for a device to respond, the kernel raises the priority of that sleep to splhigh to prevent interrupts that might cause process-state transitions. For example, see pp 84, Table 4-2 in the book, if you have a process waiting for swap (PSWP, priority 0) and you issue a kill which would run at the baseline kernel priority, PZERO (priority 22), your kill will have no effect on a process in PSWP state until that process transitions to a lower priority. > > > Also, anything that prevents root from killing a process is not right, > > IMHO. > > It is usually indicative of a deeper problem. Agreed. For example an NFS I/O running at priority PRIBIO (priority 16) cannot be killed by a process running at PZERO. The deeper problem being that a device or in this case an NFS server is not responding. Regards, Phone: (250)387-8437 Cy Schubert Fax: (250)387-5766 Team Leader, Sun/Alpha Team Internet: Cy.Schubert@osg.gov.bc.ca Open Systems Group, ITSD, ISTA Province of BC To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?200012231434.eBNEYoc09416>