Look at the information available from the kernel about current memory usage using the proc file meminfo and the command free. Also, see how to turn off and on swap space and see an example where swap space is essential.
- [Instructor] Let's look at /proc/meminfo.…Meminfo is a handy proc file.…It's maybe 46 lines of information, a lot of stuff in there.…Remember since it's a proc file,…it's always up-to-date, fresh information.…Whenever you cat it, you're asking the kernel…to generate the contents of it right then.…One thing that confuses a lot of folks is MemFree.…And you see MemFree and it's a small number…and you kind of freak out.…
But really you want it to be kind of small,…because you want the kernel to be…making use of your RAM for caching.…So it's really MemAvailable that's more important.…MemAvailable is an estimate of how much is available…for programs, without resorting to swapping,…which of course is a bad thing.…So don't worry about MemFree, worry about MemAvailable.…We see at the top MemTotal is the total amount…of RAM on your system.…And on this little system I've got about eight gig.…
And the free is kind of small, but that's okay,…but there's quite a bit available.…I'm not really running much right now.…And we see other sorts of things including,…
Author
Released
2/15/2018- Timing techniques
- Packages for performance
- Identifying and optimizing CPU bottlenecks
- Finding memory bottlenecks
- Diagnosing disk bottlenecks
Skill Level Advanced
Duration
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Introduction
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Welcome32s
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1. Performance Overview
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Timing techniques14m 16s
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Timing techniques solution3m 21s
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The proc filesystem7m 58s
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Packages for performance6m 8s
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Performance Co-Pilot and Tuna10m 23s
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2. CPU Bottlenecks
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top for CPU usage1m 43s
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sar for CPU2m 59s
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/proc/cpuinfo2m 18s
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Throughput vs. response time4m 17s
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3. Memory Bottlenecks
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What is a memory leak?6m 53s
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CPU caches and page caches12m 43s
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Page sizes and page faults11m 17s
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4. Disk Bottlenecks
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Hard disks and SSD behavior7m 21s
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Filesystem types and performance10m 16s
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Solution: Disk bottlenecks3m 49s
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Conclusion
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Next steps40s
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Video: /proc/meminfo, free, and swap space