Ior histiocytoma or mast cell tumor dog – lustre wiki

IOR is not a lustre-specific benchmark and can be run on any POSIX-compliant file system, but it does require a fully installed and configured file histiocytoma or mast cell tumor dog system implementation in order to run. For lustre, this means the MGS, MDS and OSS services must be installed, configured and running, and that there is a population of lustre client nodes histiocytoma or mast cell tumor dog running with the lustre file system mounted.

IOR can be used for testing performance of parallel file histiocytoma or mast cell tumor dog systems using various interfaces and access patterns. IOR uses MPI for process synchronisation – typically there are several IOR processes running in parallel across histiocytoma or mast cell tumor dog several nodes in an HPC cluster. As a user-space benchmarking application it is suitable for comparing the performance histiocytoma or mast cell tumor dog of different file systems. Typically one IOR process is run on each participating client histiocytoma or mast cell tumor dog node mounting the target file system but this is completely histiocytoma or mast cell tumor dog configurable.

• create a user account from which to run the application, if a suitable account does not already exist. The account must be propagated across all of the lustre histiocytoma or mast cell tumor dog client nodes that will participate in the benchmark, as well as the MDS servers for the file system. On the servers, it is recommended that the account is disabled in order histiocytoma or mast cell tumor dog to prevent users from logging into those machines.

• consider relaxing the stricthostkeychecking SSH option so that host entries histiocytoma or mast cell tumor dog are automatically added into $HOME/.Ssh/known_hosts rather than prompting the user to confirm the connection. When running MPI programs across many nodes, this can save a good deal of inconvenience. If the account home directory is not on a shared histiocytoma or mast cell tumor dog storage, all nodes will need to be updated.

This may be desirable for multi-process tests but not for the single task per client histiocytoma or mast cell tumor dog test. Do not set the slot count higher than the number histiocytoma or mast cell tumor dog of cores present. If over-subscription is required, set the -np flag to greater than the number of physical cores. This informs openmpi that the task will be oversubscribed and histiocytoma or mast cell tumor dog will run in a mode that yields the processor to histiocytoma or mast cell tumor dog peers.

Size of data block in bytes (e.G. 8, 4k, 2m, 1g). This is the size of the block of data that histiocytoma or mast cell tumor dog each process will write and must be a multiple of histiocytoma or mast cell tumor dog the transfer size. Set it to a large number. For single file tests, multiply the block size by the number of tasks to histiocytoma or mast cell tumor dog get the file size. For multiple file tasks, each file will be block size bytes. File system must have block size * nprocs free space.

When preparing the benchmark, pay careful attention to the distribution of processes across the histiocytoma or mast cell tumor dog nodes. Mpirun will, by default, fill the slots of one node before allocating processes to histiocytoma or mast cell tumor dog the next node in the list. I.E. All of the slots on the first node in the histiocytoma or mast cell tumor dog file will be consumed before allocating processes to the second histiocytoma or mast cell tumor dog node, then third node, and so on. If the number of slots requested is lower than the histiocytoma or mast cell tumor dog overall number of slots in the host file, then utlisation will not be evenly distributed, and some nodes may not be used at all.

If the number of process is larger than the number histiocytoma or mast cell tumor dog of available slots, mpirun will oversubscribe one or more nodes until all the histiocytoma or mast cell tumor dog processes have been launched. This can be exploited to create more even distribution of histiocytoma or mast cell tumor dog processes across nodes by setting the number of slots per histiocytoma or mast cell tumor dog host to 1. However, note that mpirun will decide where the additional processes will histiocytoma or mast cell tumor dog run, which can lead to performance variance from run to run histiocytoma or mast cell tumor dog of a job.

The –map-by node option distributes processes evenly across the nodes, and does not try to consume all of the slots histiocytoma or mast cell tumor dog from one node before allocating processes to the next node histiocytoma or mast cell tumor dog in the list. For example, if there are 4 nodes, each with 16 slots (64 slots total), and a job is submitted that requires only 24 slots, then each node will be allocated 6 processes.

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