IBM 000-8697 Bedienungsanleitung PDF herunterladen (Seite 579)

100

101

Utilities 7-101

Option Descriptions

The number of active users and the maximum number of users allowed are

also indicated. The maximum number of concurrent user processes is

speciﬁed as USERS in the OnLine conﬁguration ﬁle.

-X Option

Use the -X option to obtain precise information about the processes that are

sharing and waiting for buffers.

For each buffer in use,the -X option displays generalbuffer information that

is also available with either the -b or -B option. See tbstat -b for an expla-

nation of these ﬁelds.

Unique to the -X option are the sharers and waiters ﬁelds. More than one

process can share data in a buffer. For each buffer, the sharers ﬁeld lists the

addresses of all user processes sharing that buffer. During an update

operation, a process places an exclusive lock on a buffer and no sharing

occurs. In this situation, the waiters ﬁeld lists the addresses of all user

processes waiting for the buffer.

The tbstat -b and -B options contain a waitlist ﬁeld that displays the

addressoftheﬁrstuserprocesswaitingforthebuffer.The-Xoptionprovides

a complete list of addresses for all waiting processes.

The maximum number of shared buffers is speciﬁed as BUFFERS in the

OnLine conﬁguration ﬁle.

wait if the user process is waiting for a speciﬁc latch or lock, this

ﬁeld displays the address of the resource. Use this address to

map to information provided in the -s (latch) or -k (lock)

output.

tout is the lock time-out counter.

nlocks is thenumber of locks that theuser process is holding.(The -k

output should include a listing for each lock held.)

nreads is the number of read calls that the user process has executed.

The reads could be either physical reads from disk or virtual

reads from the buffer cache.

nwrites isthe number ofwritecalls that the userprocess has executed.

All write calls are writes to the shared-memory buffer cache.

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