From mboxrd@z Thu Jan 1 00:00:00 1970 From: danielhilst@gmail.com (Daniel Hilst) Date: Mon, 12 Mar 2012 11:54:18 +0000 Subject: Kernel threads and system usage metric. In-Reply-To: References: <4F59EBFF.10202@gmail.com> Message-ID: <4F5DE3EA.6010006@gmail.com> To: kernelnewbies@lists.kernelnewbies.org List-Id: kernelnewbies.lists.kernelnewbies.org On 03/09/2012 06:25 PM, Mulyadi Santosa wrote: > Hi :) > > On Fri, Mar 9, 2012 at 18:39, Daniel Hilst wrote: >> The processes that appear in top with brackets are the kernel threads? > > Yup :) > >> If so, this threads spend all its time on system mode, right? > > Yes, it supposed to ... > >> By the >> system mode I mean the %sy on top header, since kernel threads hasn't >> any memory mapped to user space, it can't run on user space at any time, >> right? > > IIRC, kernel thread simply "borrow" any previous scheduled task's > address space. In that matter, it also has user address space. So, if > wanted, kernel thread could access user space. But normally it doesn't > do it. > >> >> >> So the total of system mode usage is the sum of all processes processing >> in kernel space, plus the kernel threads processing, right? > > remember that kernel threads are also processes, so no need to > differentiate between normal processes and kernel threads, especially > when we talk about CPU utilization. > Thanks Mulyadi! -- Follow the white rabbit!