Thanks Andreas, The problem is there is a bug in WAS when DFLTCC is used - Assessment by Java Development is that Wells Fargo's symptoms line up to be the same issue as experienced by another client several days earlier. In the first client's case, they were provided with an WAS Ifix (APAR PH27505) which prevents the endless looping that occurs when the JVM API does not report that the compressed data stream has reached the end. The client tested the WAS iFix and confirmed that it does prevent the endless looping during decompression. The current recommendation is for z15 zLinux clients running JAVA8 SR6 is to apply WAS APAR PH27505 and run with HW compression disabled (DFLTCC=0).
Wells Fargo has 2000 Linux guests they would have to patch to fix and were looking for an easy way to just disable. Regards, Bill ___________________________________________________________________________________________ Bill Bitner - z/VM Client Focus and Care - 607-429-3286 bitn...@us.ibm.com "Making systems practical and profitable for customers through virtualization and its exploitation." - z/VM From: Andreas Krebbel <kreb...@linux.ibm.com> To: LINUX-390@VM.MARIST.EDU Date: 07/22/2020 07:49 AM Subject: [EXTERNAL] Re: z15 on-board compression Sent by: Linux on 390 Port <LINUX-390@VM.MARIST.EDU> Hi, I wrote a post about how to build and test zlib also for distros currently not supported: https://urldefense.proofpoint.com/v2/url?u=http-3A__linux-2Don-2Dz.blogspot.com_2019_10_howto-2Dexploiting-2Dhardware-2Dcompression.html&d=DwICaQ&c=jf_iaSHvJObTbx-siA1ZOg&r=5MoiGnRMsqjUxHq7C7RX4kthfAKqf40IRGxojgucrwA&m=x1vmZzvvtIGmEi8_Y7og3XDpzRz1wa5VLMnZ-0HDnMA&s=uQF9dwXC8luEMIVM-xxLnLikZ8q2yREoz_7unCt3O30&e= You will find a quick one-liner test at the end of the post which can be used to verify whether hardware compression works in your installation. Andreas On 10.06.20 01:36, Michael MacIsaac wrote: > Hello list, > > I heard about the new DFLTCC instruction on the z15, aka on board > compression. I tried a quick experiment to see the difference from a z14. > Disclaimer: I am not a performance expert.> > Here are three commands to create, compress and decompress a 1G file on a > z14: > > # grep Type: /proc/sysinfo > Type: 3906 > > # time dd if=/dev/zero of=1G.file bs=1G count=1 > 1+0 records in > 1+0 records out > 1073741824 bytes (1.1 GB, 1.0 GiB) copied, 21.93 s, 49.0 MB/s > > real 0m22.047s > user 0m0.001s > sys 0m3.669s > > # time cat 1G.file | gzip -c > 1G.compressed.file > > real 0m7.603s > user 0m5.362s > sys 0m0.789s > > # time cat 1G.compressed.file | gzip -d > 1G.file > > real 0m24.833s > user 0m4.103s > sys 0m1.845s > > Here's the same commands on z15: > > # grep Type: /proc/sysinfo > Type: 8561 > > # time dd if=/dev/zero of=1G.file bs=1G count=1 > 1+0 records in > 1+0 records out > 1073741824 bytes (1.1 GB, 1.0 GiB) copied, 1.59126 s, 675 MB/s > > real 0m1.621s > user 0m0.000s > sys 0m1.216s > > # time cat 1G.file | gzip -c > 1G.compressed.file > > real 0m5.722s > user 0m4.946s > sys 0m0.510s > # time cat 1G.compressed.file | gzip -d > 1G.file > > real 0m6.150s > user 0m3.922s > sys 0m1.290s > > Wow more than 10x faster on dd - was not expecting that as I didn't think > it uses compression. But the compress with gzip -c, was only 25% faster on > the z15 while the decompress was about 4x. > > Are these results expected? > > Thanks. > > > -- > -Mike MacIsaac > > ---------------------------------------------------------------------- > For LINUX-390 subscribe / signoff / archive access instructions, > send email to lists...@vm.marist.edu with the message: INFO LINUX-390 or visit > https://urldefense.proofpoint.com/v2/url?u=http-3A__www2.marist.edu_htbin_wlvindex-3FLINUX-2D390&d=DwICaQ&c=jf_iaSHvJObTbx-siA1ZOg&r=5MoiGnRMsqjUxHq7C7RX4kthfAKqf40IRGxojgucrwA&m=x1vmZzvvtIGmEi8_Y7og3XDpzRz1wa5VLMnZ-0HDnMA&s=FQsLX2gZ60YhLotQ1szspOspNp8arGQloNna6pa4DhI&e= > ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to lists...@vm.marist.edu with the message: INFO LINUX-390 or visit https://urldefense.proofpoint.com/v2/url?u=http-3A__www2.marist.edu_htbin_wlvindex-3FLINUX-2D390&d=DwICaQ&c=jf_iaSHvJObTbx-siA1ZOg&r=5MoiGnRMsqjUxHq7C7RX4kthfAKqf40IRGxojgucrwA&m=x1vmZzvvtIGmEi8_Y7og3XDpzRz1wa5VLMnZ-0HDnMA&s=FQsLX2gZ60YhLotQ1szspOspNp8arGQloNna6pa4DhI&e= ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to lists...@vm.marist.edu with the message: INFO LINUX-390 or visit http://www2.marist.edu/htbin/wlvindex?LINUX-390
