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Full Discussion: CIO/DIO and JFS2 read ahead
Operating Systems AIX CIO/DIO and JFS2 read ahead Post 302258295 by bakunin on Friday 14th of November 2008 09:13:07 AM
Old 11-14-2008
Quote:
Originally Posted by zaxxon
Also you can check about aio, if there is any usage of it or something close to it's limits with "iostat -A" and also the shift+a option in nmon, to see how many aioservers are being used currently.
pstat -a | grep [[-c]] aio

does the same - display/count the used asynchronous I/O servers. Note, though, that you have to deduct 1 from the result (the server process). Also note the correclation with the number of CPUs: The number you enter on the "chdev"-command line with the "maxservers" attribute is the number of servers per CPU. On an 8-way system the command

chdev -l aio0 -P -a maxservers=10

will cause (a maximum of) 81 aio servers (1 server process and 80 worker processes) to come into life.

I hope this helps.

bakunin
 

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aio.h(3HEAD)							      Headers							      aio.h(3HEAD)

NAME
aio.h, aio - asynchronous input and output SYNOPSIS
#include <aio.h> DESCRIPTION
The <aio.h> header defines the aiocb structure which includes the following members: int aio_fildes file descriptor off_t aio_offset file offset volatile void* aio_buf location of buffer size_t aio_nbytes length of transfer int aio_reqprio request priority offset struct sigevent aio_sigevent signal number and value int aio_lio_opcode operation to be performed This header also includes the following constants: AIO_ALLDONE A return value indicating that none of the requested operations could be canceled since they are already complete. AIO_CANCELED A return value indicating that all requested operations have been canceled. AIO_NOTCANCELED A return value indicating that some of the requested operations could not be canceled since they are in progress. LIO_NOP A lio_listio(3RT) element operation option indicating that no transfer is requested. LIO_NOWAIT A lio_listio() synchronization operation indicating that the calling thread is to continue execution while the lio_listio() operation is being performed, and no notification is given when the operation is complete. LIO_READ A lio_listio() element operation option requesting a read. LIO_WAIT A lio_listio() synchronization operation indicating that the calling thread is to suspend until the lio_listio() operation is complete. LIO_WRITE A lio_listio() element operation option requesting a write. SEE ALSO
lseek(2), read(2), write(2), fsync(3C), libaio(3LIB), lio_listio(3RT) SunOS 5.10 10 Sep 2004 aio.h(3HEAD)
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