Reputation
413
Top tag
Next privilege 500 Rep.
Access review queues
Badges
5 12
Newest
 Necromancer
Impact
~33k people reached

Jan
7
revised SSL Certificate Class 2 vs Class 3 vs Class 4
Explicitly mention that "Certificate class" exists technically only in an user visible string and has zero real world difference
Dec
22
awarded  Necromancer
Dec
10
awarded  Revival
Dec
10
awarded  Yearling
Nov
17
awarded  Excavator
Nov
17
revised Copying a large directory tree locally? cp or rsync?
remove ranting
Nov
17
suggested approved edit on Copying a large directory tree locally? cp or rsync?
Sep
7
awarded  Constituent
Aug
26
awarded  Caucus
May
6
awarded  Necromancer
Nov
18
awarded  Caucus
Sep
24
awarded  Autobiographer
Sep
15
comment Apache redirect and set cache headers?
If you want "always" headers only for selected redirects, see this: mark.koli.ch/…
Aug
28
revised SSL Certificate Class 2 vs Class 3 vs Class 4
elaborate the text a bit, fix a couple of typos
Aug
28
awarded  Revival
Aug
20
answered Difference between reboot -n and echo b > /proc/sysrq-trigger?
Aug
12
answered SSL Certificate Class 2 vs Class 3 vs Class 4
Jun
27
comment limit linux background flush (dirty pages)
Elevevator in software is a tradeoff: sacrifice latency to improve bandwidth. For example, imagine 100K write ops in the software queue submitted in random order; if the software elevator can order those ops using a huge buffer it may end up sending only 5K much bigger requests to the device. However, as a result, the latency needs to be increased by 100K ops because it may be that the first 2K ops and last 1K ops are actually near each other on the device. Without added latency, it will be impossible to merge those.
Jun
27
comment limit linux background flush (dirty pages)
Logically dirty_bytes should be barely high enough to not stall CPUs while processes are writing if the process is writing on average with the throughput of the device. If your application code is doing cycles of huge computation followed by writing huge amount of data, if will be very hard to optimize because short time averages differs greatly from long time averages. The correct solution would be to adjust process specific dirty_bytes setting but Linux does not support such thing as far as I know.
Jan
16
comment Why does “cat /dev/null” and “ls” take 5 seconds to load?
It seems that your httpd processes are pretty heavy because those eat way more CPU time than mysqld. I'd investigate if it's possible to optimize the code run by httpd processes (possibly PHP code?) to reduce CPU usage. If you have your own server room, it probably makes sense to move mysqld on a server of its own, run a reverse proxy with load balancer (recent apache with mod_proxy is fine) and run multiple httpd worker boxes in between. This is probably cheaper than getting one machine with very fast CPU.