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authorbnewbold <bnewbold@robocracy.org>2012-07-05 11:00:36 -0500
committerbnewbold <bnewbold@robocracy.org>2012-07-05 11:00:36 -0500
commit385371f1f8a4ea6430894dd9a2ec9418253afbef (patch)
treec9bb3addd8a84341e8cd92f540e2f1f9d9e0d4d4 /software
parentcc0bd3eaadd10baf96bdfab29e7c81111fb30d62 (diff)
downloadknowledge-385371f1f8a4ea6430894dd9a2ec9418253afbef.tar.gz
knowledge-385371f1f8a4ea6430894dd9a2ec9418253afbef.zip
misc additions
Diffstat (limited to 'software')
-rw-r--r--software/debian.page2
-rw-r--r--software/misc.page25
-rw-r--r--software/packages.page1
3 files changed, 28 insertions, 0 deletions
diff --git a/software/debian.page b/software/debian.page
index 16d456d..ba49a33 100644
--- a/software/debian.page
+++ b/software/debian.page
@@ -50,6 +50,8 @@ Some gotchas from installing debian a few times:
* To install emacs without an X environment, use ``emacs23-nox`` (or a more
recent version).
+ * To change time zone: ``sudo dpkg-reconfigure tzdata``
+
Debian Package Tools
------------------------------
``dkpg -S somefile`` shows what packages a given file were installed by. ``dpkg
diff --git a/software/misc.page b/software/misc.page
index 8152c92..ecedf85 100644
--- a/software/misc.page
+++ b/software/misc.page
@@ -123,3 +123,28 @@ are invisible within Inkscape but visible when exported.
To remove this box, edit the raw XML using the XML Editor in Inkscape
(Shift-Ctrl-X), look for an svg:flowRoot element within the first layer, and
delete it.
+
+Latency Numbers
+-----------------
+
+From https://gist.github.com/2841832::
+
+ L1 cache reference 0.5 ns
+ Branch mispredict 5 ns
+ L2 cache reference 7 ns 14x L1 cache
+ Mutex lock/unlock 25 ns
+ Main memory reference 100 ns 20x L2 cache, 200x L1 cache
+ Compress 1K bytes with Zippy 3,000 ns
+ Send 1K bytes over 1 Gbps network 10,000 ns 0.01 ms
+ Read 4K randomly from SSD* 150,000 ns 0.15 ms
+ Read 1 MB sequentially from memory 250,000 ns 0.25 ms
+ Round trip within same datacenter 500,000 ns 0.5 ms
+ Read 1 MB sequentially from SSD* 1,000,000 ns 1 ms 4X memory
+ Disk seek 10,000,000 ns 10 ms 20x datacenter roundtrip
+ Read 1 MB sequentially from disk 20,000,000 ns 20 ms 80x memory, 20X SSD
+ Send packet CA->Netherlands->CA 150,000,000 ns 150 ms
+
+ Notes:
+ 1 ns = 10-9 seconds
+ 1 ms = 10-3 seconds
+ * Assuming ~1GB/sec SSD
diff --git a/software/packages.page b/software/packages.page
index 99aeeb1..639c056 100644
--- a/software/packages.page
+++ b/software/packages.page
@@ -31,6 +31,7 @@ Almost all machines get the following (decreasing minimalism):
netcat
ngrep
tcpdump
+ mtr
If debian-based, add ``build-essential``, ``openssh-server``, ``manpages-dev``,
and it's ``git-core`` (not ``git``). See also [debian].