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@@ -181,12 +181,17 @@ To reduce its OS jitter, do any of the following:
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make sure that this is safe on your particular system.
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d. It is not possible to entirely get rid of OS jitter
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from vmstat_update() on CONFIG_SMP=y systems, but you
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- can decrease its frequency by writing a large value to
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- /proc/sys/vm/stat_interval. The default value is HZ,
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- for an interval of one second. Of course, larger values
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- will make your virtual-memory statistics update more
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- slowly. Of course, you can also run your workload at
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- a real-time priority, thus preempting vmstat_update().
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+ can decrease its frequency by writing a large value
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+ to /proc/sys/vm/stat_interval. The default value is
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+ HZ, for an interval of one second. Of course, larger
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+ values will make your virtual-memory statistics update
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+ more slowly. Of course, you can also run your workload
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+ at a real-time priority, thus preempting vmstat_update(),
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+ but if your workload is CPU-bound, this is a bad idea.
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+ However, there is an RFC patch from Christoph Lameter
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+ (based on an earlier one from Gilad Ben-Yossef) that
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+ reduces or even eliminates vmstat overhead for some
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+ workloads at https://lkml.org/lkml/2013/9/4/379.
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e. If running on high-end powerpc servers, build with
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CONFIG_PPC_RTAS_DAEMON=n. This prevents the RTAS
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daemon from running on each CPU every second or so.
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