kernel-packages team mailing list archive

[Dimitri John Ledkov <launchpad@xxxxxxxxxxxx>]

The following config changes will be fixed soon:
CONFIG_NUMA
CONFIG_REGMAP
CONFIG_NET_VENDOR_EMULEX
CONFIG_BE2NET
CONFIG_BE2NET_VXLAN
CONFIG_NET_VENDOR_SYNOPSYS
CONFIG_NVMEM

The requests below two keys are currently out of scope, with the generic kernel config policy for Ubuntu:
CONFIG_PREEMPT_NONE
CONFIG_SCSI_SCAN_ASYNC

We ship PREEMPT_VOLUNTARY & CONFIG_SCSI_SCAN_ASYNC on all architectures
(including ppc64, ppc64el, and s390x) and this is what we support and
have shipped at least since lucid (6 years +). If you really want to
escalate changes to these two config keys from what Ubuntu users expect
on Ubuntu, please provide details of fundamental s390x architecture
specific difference that result in worse generic performance when
configured like we currently have; or for example why that's the wrong
thing to do across all architectures. To me, both of those config keys
are more-or-less architecture-agnostic and in general improve
performance without significant performance impacts. BTW, IBM z/KVM
appears to ship with CONFIG_SCSI_SCAN_ASYNC=y too.

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https://bugs.launchpad.net/bugs/1543165

Title:
  kernel: update kernel configuration

Status in linux package in Ubuntu:
  Triaged

Bug description:
  == Comment: #0 - Hendrik Brueckner <brueckner@xxxxxxxxxx> - 2016-02-08 09:41:49 ==
  The below mentioned kernel configuration options are still not yet integrated into the Ubuntu kernel. In addition to the discussions on the skipper mailing list, hereby the bugzilla / launchpad to integrate and update the kernel configuration.

  > Short explaination for all requested changes:                                                                                                           
  >                                                                                                                                                         
  > CONFIG_NUMA (and all related config options):                                                                                                           
  > s390 gained fake NUMA support with kernel version 4.3. Performance                                                                                      
  > measurements did show that this helps for very large machines (lot's of                                                                                 
  > memory), and also doesn't hurt for small machines.  Therfore the config                                                                                 
  > option should be enabled.                                                                                                                               
  >                                                                                                                                                         
  > CONFIG_PREEMPT_NONE:                                                                                                                                    
  > We only have performance numbers for non-preemptible kernels. While kernel                                                                              
  > preemption generally should work from a functional point of view on s390,                                                                               
  > we do not have numbers about the performance costs. Nor do we have any                                                                                  
  > production systems running with kernel preemption enabled currently.                                                                                    
  > Therefore let's please switch to PREEMPT_NONE which has proven to work.                                                                                 
  >                                                                                                                                                         
  > CONFIG_SCSI_SCAN_ASYNC:                                                                                                                                 
  > Hendrik already requested to disable this config option.                                                                                                
  >                                                                                                                                                         
  > CONFIG_REGMAP,                                                                                                                                          
  > CONFIG_NET_VENDOR_EMULEX,                                                                                                                               
  > CONFIG_BE2NET,                                                                                                                                          
  > CONFIG_BE2NET_VXLAN,                                                                                                                                    
  > CONFIG_NET_VENDOR_SYNOPSYS,                                                                                                                             
  > CONFIG_NVMEM:                                                                                                                                           
  > Looks like all of these crept in with the kernel update to 4.3. None of                                                                                 
  > these are relevant to s390 and can be disabled.                                                                                                         

  An updated config patch to the kernel version above will be added

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