Date: Wed, 15 May 2002 14:07:05 -0400 (EDT) From: Zhihui Zhang <zzhang@cs.binghamton.edu> To: Alfred Perlstein <bright@mu.org> Cc: Terry Lambert <tlambert2@mindspring.com>, Doug White <dwhite@resnet.uoregon.edu>, freebsd-hackers@FreeBSD.ORG Subject: Re: Collect process sleeping statistics Message-ID: <Pine.SOL.4.21.0205151400480.17950-100000@onyx> In-Reply-To: <20020515174609.GK1585@elvis.mu.org>
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What if most I/O are asynchronous writes and handled by a background process (e.g. SoftUpdate syncer daemon or a special kernel daemon), then I guess the wait should have something to do with memory or buffer. But I do not know to to confirm this. Maybe some profiling or instrumentation (too much work?) will help. -Zhihui On Wed, 15 May 2002, Alfred Perlstein wrote: > * Zhihui Zhang <zzhang@cs.binghamton.edu> [020515 10:33] wrote: > > > > Basically I have a program that does a lot of I/O and alloctes/frees a lot > > of memory. The time command gives result like this: > > > > 6.239u 19.329s 7:59.76 5.3% 310+775k 3993+246io 7pf+0w > > > > I want to know why CPU is running only 5.3% of the total time. I just > > want know how long it is waiting for memory and how long it is waiting for > > I/O. No other process is running at the same time. > > When not condending against other processes, almost all time not > spent on CPU is waiting for IO. > > -Alfred > > To Unsubscribe: send mail to majordomo@FreeBSD.org > with "unsubscribe freebsd-hackers" in the body of the message > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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