Brendan Gregg > Quotes

“Beyond 60% utilization, the average response time doubles. By 80%, it has tripled. As disk I/O latency is often the bounding resource for an application, increasing the average latency by double or higher can have a significant negative effect on application performance. This is why disk utilization can become a problem well before it reaches 100%, as it is a queueing system where requests (typically) cannot be interrupted and must wait their turn.”
― Brendan Gregg, Systems Performance: Enterprise and the Cloud

“2. Methodology”
― Brendan Gregg, Systems Performance: Enterprise and the Cloud

“which is a unique numeric identifier. A process contains one or more threads, which operate in the process address space and share the same file descriptors (state describing open files).”
― Brendan Gregg, Systems Performance: Enterprise and the Cloud

“It was later updated2 and”
― Brendan Gregg, DTrace: Dynamic Tracing in Oracle Solaris, Mac OS X and FreeBSD

“However, if application A is opaque and application B provides a rich set of observability tools, it’s very likely that application B will be the better choice in the long run.”
― Brendan Gregg, Systems Performance: Enterprise and the Cloud