** Description changed:
+ [Feature Freeze Exception]
+
+ 1. Feature:
+
+ The latest s390x hardware comes with a new concept for hardware assisted
+ compression/decompression, based on a 'Next Accelerator Function unit'
+ (NXU). This is an on-chip concept, a co-processor for compression
+ available to all cores on the same chip. It provides functions as normal
+ 'problem state' instructions (in other words user space instructions
+ that are directly consumable by libraries and applications) and supports
+ DEFLATE compliant compression/decompression + GZIP CRC/ZLIB Adler.
+
+ To enable this hardware support for zlib and gzip, zlib needs to be compiled
with CFLAGS="-O2 -DDFLTCC -DDFLTCC_LEVEL_MASK=0x7e".
+ The value of 0x7e enables hardware compression for the compression levels 1-6
(out of 0-9).
+ There is a significant business value of having the enablement active by
default, since tests on a system with 4 IFLs and hardware compression enabled
this way offered (especially for DEFLATE as best case) a speed up of more than
40x.
+
+ 2. Changes
+
+ Adding CFLAGS="-O2 -DDFLTCC -DDFLTCC_LEVEL_MASK=0x7e" attributes/macro
+ during build of zlib and gzip.
+
+ 3. Regression risk
+
+ The concept is new and comes with IBM z15 and LinuxONE III only and is with
that specific and limited to s390x.
+ Hence a potential regressions of this late addition would be limited to s390x
and there again with the above changes to zlib (and gzip).
+ In case of unforeseen issues with the NXU hardware component, a fallback to
software is done.
+ On top a modified zlib package was build and made available in a PPA for
further testing.
+ This change should have been included earlier, but was blocked by other zlib
tickets/bugs that needed to be fixed and integrated first (like LP 1893170),
hence this request for late addition.
+ __
+
HW Compression need to be enabled with Default-Compression-Level 6.
- Adding following CFLAGS attributes during build of zlib and gzip
- "-DDFLTCC_LEVEL_MASK=0x7e"
-
+ Adding following CFLAGS attributes during build of zlib and gzip
+ "-DDFLTCC_LEVEL_MASK=0x7e"
CFLAGS="-O2 -DDFLTCC -DDFLTCC_LEVEL_MASK=0x7e" ./configure
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https://bugs.launchpad.net/bugs/1884514
Title:
[20.10 FEAT] zlib/gzip hardware compression enablement
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