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| author | bnewbold <bnewbold@robocracy.org> | 2012-07-05 11:00:36 -0500 |
|---|---|---|
| committer | bnewbold <bnewbold@robocracy.org> | 2012-07-05 11:00:36 -0500 |
| commit | 385371f1f8a4ea6430894dd9a2ec9418253afbef (patch) | |
| tree | c9bb3addd8a84341e8cd92f540e2f1f9d9e0d4d4 /software | |
| parent | cc0bd3eaadd10baf96bdfab29e7c81111fb30d62 (diff) | |
| download | knowledge-385371f1f8a4ea6430894dd9a2ec9418253afbef.tar.gz knowledge-385371f1f8a4ea6430894dd9a2ec9418253afbef.zip | |
misc additions
Diffstat (limited to 'software')
| -rw-r--r-- | software/debian.page | 2 | ||||
| -rw-r--r-- | software/misc.page | 25 | ||||
| -rw-r--r-- | software/packages.page | 1 |
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]. |