22,188 reputation
12450
bio website ripplelabs.com
location Oakland, California
age 45
visits member for 3 years, 5 months
seen 4 hours ago

I am Chief Cryptographer at Ripple Labs and one of the architects of the Ripple payment system.


6h
comment why is my server fork rate increased?
Look for changes in the process table.
20h
comment Apache accepting requests to other servers?
Welcome to the Internet. Everyone who operates a server on the Internet has to have a strategy for dealing with the "baseline noise" that pretty much all Internet servers see.
Jan
21
comment Apache 2.4 prefork, MySQL 5.6 and 2GB RAM
Your top output shows 1.4GB of RAM (68%) inactive, which means it's available for use for any purpose. Why do you think there's a problem?
Jan
13
comment kworker consuming +90% IO and zero disk write
You may want to use perf to find out what kworker is doing as a troubleshooting step.
Jan
13
comment Where is my RAM going?
Use slabtop to see if it's the dentry cache.
Jan
12
comment High process count and load
The first question is -- what are those 1,877 processes?
Jan
7
comment Linux is sending ARP requests to hosts in other subnets?
Something is probably wrong in the netmasks or routing table on host A.
Jan
6
comment Where did my RAM go?
@mirabilos I explained the issue and gave a link to an example of something that could cause it. The example was extra, not needed to understand the answer. (It just happened, by sheer luck, to be exactly the same cause as his.) Other people who have the same issue as him likely won't have the same cause, so it doesn't really improve the answer to go into more detail. But feel free to propose an edit.
Jan
6
comment svchost.exe -k regsvc using over 1.2 GB RAM
How did you determine that it was using over 1.2 GB of RAM? (Please be as specific as possible. What tool did you use? What exactly did it report?)
Jan
5
comment Where did my RAM go?
@Benjamin I don't know any way to see what's in the dentry cache. But running strace may be instructive. Do you use libcurl? What's your app doing?
Jan
5
comment Where did my RAM go?
@Benjamin Follow my link for one example of how this can happen. Also, look at what the web application is actually doing.
Jan
2
comment Clearing Memory (RAM) Cache on CentOS
Are you seriously asking how to get your computer to waste more memory rather than using it efficiently?
Jan
2
comment How many bits of entropy per byte read from /dev/random and /dev/urandom?
@DanielKauffman I have no idea what that means.
Jan
2
comment How many bits of entropy per byte read from /dev/random and /dev/urandom?
@DanielKauffman You can already read however many bytes you want/need from /dev/urandom directly. Hashing is really only helpful if you want to combine entropy from multiple sources.
Dec
30
comment Data Transfer Speed Hardware Config
@Alan When it maxed out, what maxed out? CPU? Memory? I/O?
Dec
30
comment multiple internet connection at office
@Krunal Support for enterpricey features like tunnels.
Dec
24
comment Iptables block connection from specific IP - to another IP
@Beginner Something is very wrong with your understanding of something because the comment above is incoherent. What does it mean for a host name to use an IP address as a DNS server? And what traffic are you trying to block? Traffic to a DNS server?
Dec
16
comment HP Procurve 2920 VLANs with DHCP cannot ping
That doesn't make sense. If the server already has an IP address inside 192.168.x.0, it shouldn't need a route. And if it doesn't have an IP address inside 192.168.x.0, it shouldn't know how to reach 192.168.x.2 without a route that would also work for the rest of 192.168.x.0/24.
Dec
11
comment Swap 99% but regular memory fine
What is swappiness set to?
Dec
11
comment Swap 99% but regular memory fine
Right. It seems like his system is making a rational tradeoff. It doesn't have an awful lot of RAM, so it's moving rarely used stuff to swap to make more physical RAM available. The tradeoff is that when rarely used stuff is actually used, there's a performance hit. The benefit is that the most used stuff is faster.