jm + vm   10

The mysterious case of the Linux Page Table Isolation patches | Hacker News
good HN comments on the horrible security bug du jour -- Intel CPUs potentially allowing privileged data leaks cross-VM and cross-process
lpt  linux  vm  intel  cpus  security 
11 weeks ago by jm
TL;DR: Cassandra Java Huge Pages
Al Tobey does some trial runs of -XX:+AlwaysPreTouch and -XX:+UseHugePages
jvm  performance  tuning  huge-pages  vm  ops  cassandra  java 
february 2015 by jm
Breaking Spotify DRM with PANDA
Reverse engineering a DRM implementation, by instrumenting a VM and performing entropy/compressability analysis on function call inputs and outputs. Impressive
reversing  spotify  drm  panda  vm  compression  entropy  compressability  qemu  via:hn 
july 2014 by jm
Response to "Optimizing Linux Memory Management..."
A follow up to the LinkedIn VM-tuning blog post at --
Do not read in to this article too much, especially for trying to understand how the Linux VM or the kernel works.  The authors misread the "global spinlock on the zone" source code and the interpretation in the article is dead wrong.
linux  tuning  vm  kernel  linkedin  memory  numa 
october 2013 by jm
metric collectors for various stuff not (or poorly) handled by other monitoring daemons

Core of the project is a simple daemon (harvestd), which collects metric values and sends them to graphite carbon daemon (and/or other configured destinations) once per interval. Includes separate data collection components ("collectors") for processing of:

/proc/slabinfo for useful-to-watch values, not everything (configurable).
/proc/vmstat and /proc/meminfo in a consistent way.
/proc/stat for irq, softirq, forks.
/proc/buddyinfo and /proc/pagetypeinfo (memory fragmentation).
/proc/interrupts and /proc/softirqs.
Cron log to produce start/finish events and duration for each job into a separate metrics, adapts jobs to metric names with regexes.
Per-system-service accounting using systemd and it's cgroups.
sysstat data from sadc logs (use something like sadc -F -L -S DISK -S XDISK -S POWER 60 to have more stuff logged there) via sadf binary and it's json export (sadf -j, supported since sysstat-10.0.something, iirc).
iptables rule "hits" packet and byte counters, taken from ip{,6}tables-save, mapped via separate "table chain_name rule_no metric_name" file, which should be generated along with firewall rules (I use this script to do that).

Pretty exhaustive list of system metrics -- could have some interesting ideas for Linux OS-level metrics to monitor in future.
graphite  monitoring  metrics  unix  linux  ops  vm  iptables  sysadmin 
june 2013 by jm
vmtouch - the Virtual Memory Toucher
'vmtouch is a tool for learning about and controlling the file system cache of unix and unix-like systems. It is BSD licensed.'
vmtouch  vm  linux  unix  fs  filesystems  instagram 
december 2011 by jm
The MySQL “swap insanity” problem and the effects of the NUMA architecture
very interesting; modern multicore x86 architectures use a NUMA memory architecture, which can cause a dip into swap, even when there appears to be plenty of free RAM available
linux  memory  mysql  optimization  performance  swap  tuning  vm  numa  swap-insanity  swapping  from delicious
september 2010 by jm
Why WeakHashMap Sucks
'SoftReferences are the cheap, crappy caching mechanism [...] perfect for when you'd like your cache to be cleared at random times and in random order.'
softreferences  weakreferences  weak  references  gc  java  jvm  caching  hash  memory  collections  vm  weakhashmap  via:spyced  from delicious
september 2009 by jm
'an online compiler/interpreter, and a simple collaboration tool. It's a pastebin that executes code for you. You paste your code, and codepad runs it and gives you a short URL you can use to share it.' supports C, C++, D, Haskell, Lua, OCaml, PHP, Perl, Python, Ruby, Scheme, and Tcl code; isolated by a geordi-based supervisor, in turn running inside a firewalled virt, in turn running inside a firewalled dom0. nice work!
codepad  vm  jails  infrastructure  security  via:waxy  c  languages  programming  sandbox  pastebin 
august 2009 by jm

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