Date: Sun, 17 Mar 2013 19:24:28 +0000 (UTC) From: Eitan Adler <eadler@FreeBSD.org> To: src-committers@freebsd.org, svn-src-projects@freebsd.org Subject: svn commit: r248439 - projects/counters/share/man/man9 Message-ID: <201303171924.r2HJOTXj020357@svn.freebsd.org>
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Author: eadler Date: Sun Mar 17 19:24:28 2013 New Revision: 248439 URL: http://svnweb.freebsd.org/changeset/base/248439 Log: English language changes Approved by: glebius (implicit) Modified: projects/counters/share/man/man9/counter.9 Modified: projects/counters/share/man/man9/counter.9 ============================================================================== --- projects/counters/share/man/man9/counter.9 Sun Mar 17 19:12:01 2013 (r248438) +++ projects/counters/share/man/man9/counter.9 Sun Mar 17 19:24:28 2013 (r248439) @@ -49,38 +49,39 @@ .Fn SYSCTL_COUNTER_U64 parent nbr name access ptr val descr .Fn SYSCTL_ADD_COUNTER_U64 ctx parent nbr name access ptr descr .Sh DESCRIPTION -The .Nm -is a generic facility, which allows to create counters, -that can be utilized to collect statistical data or for other purposes. +is a generic facility to create counters +that can be utilized for purpose (such as collecting statistical +data). A .Nm is guaranteed to be lossless when several kernel threads do simultaneous -update. +updates. However, .Nm does not imply any .Xr locking 9 , -neither any +or .Xr atomic 9 -operations, thus are expected to be fast. +operations and are therefore expected to be fast. Moreover, .Nm -has special optimisations for SMP environment making +has special optimisations for SMP environments making .Nm -update faster than simple "+=" or "++" operation. +update faster than simple addition operations. .Bl -tag -width indent .It Fn counter_u64_alloc how Allocate a new 64-bit unsigned counter. The .Fa wait -argument is +argument is the .Xr malloc 9 wait flag, should be either .Va M_NOWAIT or .Va M_WAITOK . -With no-wait semantics operation may fail. +If +.Va M_WAITOK is specified the operation may fail. .It Fn counter_u64_free cnt Free previously allocated .Nm @@ -97,14 +98,14 @@ Subtract value of from .Nm .Fa cnt . -API doesn't guarantee any protection from underflow. +The API does not guarantee any protection from underflow. See .Sx IMPLEMENTATION DETAILS . .It Fn counter_u64_fetch cnt Obtain current snapshot of the data collected in .Nm .Fa cnt . -The data obtained isn't guaranteed to be precise. +The data obtained is not guaranteed to be precise. .It Fn counter_u64_zero cnt Clear data collected in .Nm @@ -144,7 +145,7 @@ These are allocated using .Va UMA_ZONE_PCPU .Xr uma 9 zone. -Update operation touches only the field that is private to current CPU. +The update operation only touches the field that is private to current CPU. Fetch operation loops through all per-CPU fields and obtains a snapshot sum of all fields. .Pp
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