A cgroup's memory.stat file lists the page cache usage for that cgroup (in cache and total_cache fields). How is the page cache usage derived? For example, file a.txt is opened by both cgroup A and B. Do A and B both maintain their own cache of a.txt? Or is the cache of a.txt shared between A and B? If it's shared, will memory.stat's page cache usage for both A and B be incremented by the same amo

On one of my servers I've noticed really delay on SSH logins. Connecting using the ssh -vvv options the delay occurs at debug1: Entering interactive session. extract of connection: debug1: Authentication succeeded (publickey). Authenticated to IP_REDACTED ([IP_REDACTED]:22). debug1: channel 0: new [client-session] debug3: ssh_session2_open: channel_new: 0 debug2: channel 0: send open debug1: Reque

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I'm able to use limit_req to rate-limit all requests to my server. However I'd like to remove the rate restriction for certain IP addresses (i.e. whitelist) and use a different rate restriction for certain others (i.e. certain IPs I'd like as low as 1r/s). I tried using conditionals (e.g. if ( $remote_addr = "1.2.3.4" ) {}) but that seems to work only with rewrite rules, not for rate-limit rules.

I'm trying to get these 2 location directives working in Nginx but I'm getting some errors back when booting Nginx. location ~ ^/smx/(test|production) { proxy_pass http://localhost:8181/cxf; } location ~ ^/es/(test|production) { proxy_pass http://localhost:9200/; } This is the error I'm receiving: nginx: [emerg] "proxy_pass" cannot have URI part in location given by regular expression, or inside n

How do I check what options are compiled into a Linux kernel without looking at /boot/config-* and if I don't have access to the /boot/config-* file that's left over?

I’m trying to improve my TCP throughput over a “gigabit network with lots of connections and high traffic of small packets”. My server OS is Ubuntu 11.10 Server 64bit. There are about 50.000 (and growing) clients connected to my server through TCP Sockets (all on the same port). 95% of of my packets have size of 1-150 bytes (TCP header and payload). The rest 5% vary from 150 up to 4096+ bytes. Wit

We are running HAProxy to direct mysql traffic from PHP to a set of mysql servers. However, due to an issue with the way the mysql-client sends TCP packets, we get a ton of connections in TIME_WAIT with concurrent port utilization at 50k+, and end up with SOCKERR messages on HAProxy due to port exhaustion under extremely heavy load as described here - http://blog.haproxy.com/2012/12/12/haproxy-hig

we are seeing the following: [root@primary data]# netstat -s | grep buffer ; sleep 10 ; netstat -s | grep buffer 20560 packets pruned from receive queue because of socket buffer overrun 997586 packets collapsed in receive queue due to low socket buffer 20587 packets pruned from receive queue because of socket buffer overrun 998646 packets collapsed in receive queue due to low socket buffer [root@p