IBM Power System S822LC Installing The System And Ordered Parts page 71

bandwidth reduces the latency for a single compression job significantly. Its aggregate throughput allows
the adapter to keep pace with common I/O traffic and offers reduced data for storage and network
traffic. Additionally, the adapter has no impact on most I/O traffic and in some cases will have a positive
effect. The adapter also enables good standard compression in cases where software overhead prevents it.
To achieve the best performance gain, strive for data block sizes larger than 64 KB, or combine smaller
blocks before sending them to hardware. The accelerated zlib library has a selectable buffering feature
built-in as well. For a graphic of the full-height adapter, see Figure 52 on page 56
Important: Graphics processing units (GPUs) and Coherent Accelerator Processor Interface (CAPI)
adapters cannot be replaced with the power on.
The following are examples of typical applications that can benefit from compression acceleration:
v Store or transmit large amounts of data that average over 100 MB/s
v Applications that need a high average throughput of data compressed
v Handling high peak throughput of data when software compression is limited
v When low latency for individual compression streams is required and it is more difficult to run in
parallel on many CPUs
v When the standard DEFLATE compression format is required for interchange as used in gzip, zlib, zip,
or JAR (Software compression methods such as LZ4 or LZS with lower compression ratios and high
bandwidth on CPUs are not an option in that case)
v Compression or a mix of compression and decompression is the main bottleneck (Decompression alone
can sometimes still be done in software with many cores in parallel)
Note: The adapter supports full speed decompression for all compliant compressed input regardless of
whether it was compressed by hardware or software.
For details about slot priorities and placement rules, see PCIe adapter placement rules and slot priorities
(http://www.ibm.com/support/knowledgecenter/POWER8/p8eab/p8eab_mtm_pciplacement.htm) and
select the system you are working on.
Installing and configuring system features
55