** 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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