D27362: Linux/cpuinfo.c: bump CPUINFOBUFSIZE for 12+ core CPUs

[Jakob Kummerow]

jakobkummerow created this revision.
jakobkummerow added a reviewer: davidedmundson.
Herald added a project: Plasma.
Herald added a subscriber: plasma-devel.
jakobkummerow requested review of this revision.

REVISION SUMMARY
  Getting CPU information starts with reading /proc/cpuinfo into a buffer; if that buffer is too small, then no information will be returned at all (updateCpuInfo() will return -1, so initCpuInfo() will return early); the consequence is that ksysguardd/ksysguard/plasmaengineexplorer won't know about "system/cores" or "cpu/system/AverageClock"; that in turn will make the "System Load Viewer" plasmoid completely dysfunctional (it won't show *any* data) because it relies on "system/cores" being available.
  
  The buffer is currently 32KB large, which is not enough on modern hardware. This patch bumps it to 256K, in order to accommodate current hardware and be future-proof for a few years.
  
  I can provide two specific data points, measured with `cat /proc/cpuinfo | wc -c`:
  
  - on a 12C24T AMD machine: ~36K
  - on a 36C72T Intel machine: ~102K
  
  Extrapolating, I estimate that the biggest CPUs available today (Ryzen 3990, 64C128T) will need ~192K (but I don't have one of those available to test on).
  
  I've verified locally that this patch fixes the issue: the System Log Viewer plasmoid shows data as expected afterwards.
  
  Ref: https://bugs.kde.org/show_bug.cgi?id=384515

REPOSITORY
  R106 KSysguard

REVISION DETAIL
  https://phabricator.kde.org/D27362

AFFECTED FILES
  ksysguardd/Linux/cpuinfo.c

To: jakobkummerow, davidedmundson
Cc: plasma-devel, Orage, LeGast00n, The-Feren-OS-Dev, cblack, jraleigh, zachus, fbampaloukas, GB_2, ragreen, ZrenBot, ngraham, alexeymin, himcesjf, lesliezhai, ali-mohamed, jensreuterberg, abetts, sebas, apol, ahiemstra, mart
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