The changes landed in groovy proposed:
zlib1g | 1:1.2.11.dfsg-2ubuntu3 | groovy-proposed | s390x
hence updating status to Fix Committed.
** Changed in: zlib (Ubuntu)
Status: Triaged => Fix Committed
** Changed in: ubuntu-z-systems
Status: In Progress => Fix Committed
** No longer affects: gzip (Ubuntu)
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https://bugs.launchpad.net/bugs/1884514
Title:
[FFe][20.10 FEAT] zlib/gzip hardware compression enablement
Status in Ubuntu on IBM z Systems:
Fix Committed
Status in zlib package in Ubuntu:
Fix Committed
Bug description:
[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"
CFLAGS="-O2 -DDFLTCC -DDFLTCC_LEVEL_MASK=0x7e" ./configure
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