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MISC

  • /etc/ld.so.preload: GLIBC uses access() to check if this file exist (normally it does not exist)1. This is something related to LD_PRELOAD: If both LD_PRELOAD and /etc/ld.so.preload are employed, the libraries specified by LD_PRELOAD are preloaded first. /etc/ld.so.preload has a system-wide effect, causing the specified libraries to be preloaded for all programs that are executed on the system2.

  • I was reading a FAST18 paper (Fail-Slow Datacenter). I found it quite interesting and some suggestions are very useful for all system designers. Especially:

    • Make implicit error-masking explicit. DO NOT FAIL SILENTLY. Since this is not a fail-stop (binary) issue, normally system designers will not raise exceptions. System designers should be aware of uncommon situations, raise explicit exceptions to convert a fail-slow (non-binary) case to a fail-stop (binary) case .Actually, this also reminds the email by Linus Torvards on BUG_ON usage3.
    • Exposing performance statistic information for all-level (device, firmware, system software, application). However, based on my own experience, do not generate too much useless logs, it will just help to hide the root cause.

  • Testing of applications is often done on a testing environment, smaller in size (perhaps only a single server) and less loaded than the “live” environment. The replication behavior of such an installation may differ from a live environment in ways that mean that replication lag is unlikely to be observed in testing - masking replication-sensitive bugs.

  • mmap PROT_NONE is really used by applications, or library. They have their special usage.

  1. etc/ld.so.preload ↩

  2. ld.so.8.html ↩

  3. LKML:BUG_ON ↩

Last update: April 10, 2018

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