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IO accounting

10 bytes added, 11:40, 25 May 2008
New resources
The following resources are accounted:
; read bytes
: is the amount number of bytes read by tasks. Reads are always synchronous in the kernel so this type of resources resource is the easiest one.
; dirty bytes
: is the amount number of bytes that were dirty since VE start, i. e. data that isn't yet flushed to disk. This type of resources resource is accounted accumulated using [[RSS_fractions_accounting|page beancounters]] and the context the page was dirtied by is determined like this:
:* if a page is mapped it's "mapper" is used as this may happen in any context (unmapping of a page under memory pressure);
:* if a page is not mapped — current BC is used as this can happen during usual write (writev) only.
; written bytes
: is the amount number of bytes flushed to disk. The beancounter to charge charged with this to is the one by which the page was dirtied by.
; canceled bytes
: is the amount number of bytes that were dirty but weren't flushed to disk.
; missed bytes
: is the amount number of bytes that were dirtied but the context (beancounter) wasn't saved due to lack of memory.
== Proc interface ==
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