diff options
Diffstat (limited to 'jemalloc/doc/jemalloc.3.in')
| -rw-r--r-- | jemalloc/doc/jemalloc.3.in | 131 |
1 files changed, 52 insertions, 79 deletions
diff --git a/jemalloc/doc/jemalloc.3.in b/jemalloc/doc/jemalloc.3.in index 321e95f..1ea93bf 100644 --- a/jemalloc/doc/jemalloc.3.in +++ b/jemalloc/doc/jemalloc.3.in @@ -38,7 +38,7 @@ .\" @(#)malloc.3 8.1 (Berkeley) 6/4/93 .\" $FreeBSD: head/lib/libc/stdlib/malloc.3 182225 2008-08-27 02:00:53Z jasone $ .\" -.Dd March 14, 2010 +.Dd March 17, 2010 .Dt JEMALLOC 3 .Os .Sh NAME @@ -378,13 +378,15 @@ will disable dirty page purging. @roff_tcache@.It H @roff_tcache@Enable/disable thread-specific caching. @roff_tcache@When there are multiple threads, each thread uses a -@roff_tcache@thread-specific cache for small and medium objects. +@roff_tcache@thread-specific cache for objects up to a certain size. @roff_tcache@Thread-specific caching allows many allocations to be satisfied @roff_tcache@without performing any thread synchronization, at the cost of @roff_tcache@increased memory use. @roff_tcache@See the @roff_tcache@.Dq G -@roff_tcache@option for related tuning information. +@roff_tcache@and +@roff_tcache@.Dq M +@roff_tcache@options for related tuning information. @roff_tcache@This option is enabled by default. @roff_prof@.It I @roff_prof@Double/halve the average interval between memory profile dumps, as @@ -426,16 +428,15 @@ The default chunk size is 4 MiB. @roff_prof@See the @roff_prof@.Dq F option for information on analyzing heap profile output. @roff_prof@This option is disabled by default. -.It M -Double/halve the size of the maximum medium size class. -The valid range is from one page to one half chunk. -The default value is 32 KiB. +@roff_tcache@.It M +@roff_tcache@Double/halve the maximum size class to cache. +@roff_tcache@At a minimum, all small size classes are cached, and at a maximum +@roff_tcache@all large size classes are cached. +@roff_tcache@The default maximum is 32 KiB. .It N Double/halve the number of arenas. -The default number of arenas is -@roff_tcache@two -@roff_no_tcache@four -times the number of CPUs, or one if there is a single CPU. +The default number of arenas is four times the number of CPUs, or one if there +is a single CPU. @roff_swap@.It O @roff_swap@Over-commit memory as a side effect of using anonymous @roff_swap@.Xr mmap 2 @@ -550,9 +551,9 @@ However, it may make sense to reduce the number of arenas if an application does not make much use of the allocation functions. .Pp @roff_tcache@In addition to multiple arenas, this allocator supports -@roff_tcache@thread-specific caching for small and medium objects, in order to -@roff_tcache@make it possible to completely avoid synchronization for most small -@roff_tcache@and medium allocation requests. +@roff_tcache@thread-specific caching for small objects, in order to make it +@roff_tcache@possible to completely avoid synchronization for most small +@roff_tcache@allocation requests. @roff_tcache@Such caching allows very fast allocation in the common case, but it @roff_tcache@increases memory usage and fragmentation, since a bounded number of @roff_tcache@objects can remain allocated in each thread cache. @@ -563,27 +564,23 @@ Chunks are always aligned to multiples of the chunk size. This alignment makes it possible to find metadata for user objects very quickly. .Pp -User objects are broken into four categories according to size: small, medium, -large, and huge. +User objects are broken into three categories according to size: small, large, +and huge. Small objects are smaller than one page. -Medium objects range from one page to an upper limit determined at run time (see -the -.Dq M -option). Large objects are smaller than the chunk size. Huge objects are a multiple of the chunk size. -Small, medium, and large objects are managed by arenas; huge objects are managed +Small and large objects are managed by arenas; huge objects are managed separately in a single data structure that is shared by all threads. Huge objects are used by applications infrequently enough that this single data structure is not a scalability issue. .Pp Each chunk that is managed by an arena tracks its contents as runs of -contiguous pages (unused, backing a set of small or medium objects, or backing -one large object). +contiguous pages (unused, backing a set of small objects, or backing one large +object). The combination of chunk alignment and chunk page maps makes it possible to determine all metadata regarding small and large allocations in constant time. .Pp -Small and medium objects are managed in groups by page runs. +Small objects are managed in groups by page runs. Each run maintains a bitmap that tracks which regions are in use. @roff_tiny@Allocation requests that are no more than half the quantum (8 or 16, @roff_tiny@depending on architecture) are rounded up to the nearest power of @@ -603,13 +600,7 @@ Allocation requests that are more than the minimum subpage-multiple size class, but no more than the maximum subpage-multiple size class are rounded up to the nearest multiple of the subpage size (256). Allocation requests that are more than the maximum subpage-multiple size class, -but no more than the maximum medium size class (see the -.Dq M -option) are rounded up to the nearest medium size class; spacing is an -automatically determined power of two and ranges from the subpage size to the -page size. -Allocation requests that are more than the maximum medium size class, but small -enough to fit in an arena-managed chunk (see the +but small enough to fit in an arena-managed chunk (see the .Dq K option), are rounded up to the nearest run size. Allocation requests that are too large to fit in an arena-managed chunk are @@ -838,13 +829,6 @@ See the option. .Ed .\"----------------------------------------------------------------------------- -.It Sy "opt.lg_medium_max (size_t) r-" -.Bd -ragged -offset indent -compact -See the -.Dq M -option. -.Ed -.\"----------------------------------------------------------------------------- .It Sy "opt.lg_dirty_mult (ssize_t) r-" .Bd -ragged -offset indent -compact See the @@ -900,11 +884,6 @@ Subpage size class interval. Page size. .Ed .\"----------------------------------------------------------------------------- -.It Sy "arenas.medium (size_t) r-" -.Bd -ragged -offset indent -compact -Medium size class interval. -.Ed -.\"----------------------------------------------------------------------------- .It Sy "arenas.chunksize (size_t) r-" .Bd -ragged -offset indent -compact Chunk size. @@ -952,15 +931,10 @@ Minimum subpage-spaced size class. Maximum subpage-spaced size class. .Ed .\"----------------------------------------------------------------------------- -.It Sy "arenas.medium_min (size_t) r-" -.Bd -ragged -offset indent -compact -Minimum medium-spaced size class. -.Ed -.\"----------------------------------------------------------------------------- -.It Sy "arenas.medium_max (size_t) r-" -.Bd -ragged -offset indent -compact -Maximum medium-spaced size class. -.Ed +@roff_tcache@.It Sy "arenas.tcache_max (size_t) r-" +@roff_tcache@.Bd -ragged -offset indent -compact +@roff_tcache@Maximum thread-cached size class. +@roff_tcache@.Ed .\"----------------------------------------------------------------------------- .It Sy "arenas.ntbins (unsigned) r-" .Bd -ragged -offset indent -compact @@ -982,16 +956,16 @@ Number of cacheline-spaced bin size classes. Number of subpage-spaced bin size classes. .Ed .\"----------------------------------------------------------------------------- -.It Sy "arenas.nmbins (unsigned) r-" -.Bd -ragged -offset indent -compact -Number of medium-spaced bin size classes. -.Ed -.\"----------------------------------------------------------------------------- .It Sy "arenas.nbins (unsigned) r-" .Bd -ragged -offset indent -compact Total number of bin size classes. .Ed .\"----------------------------------------------------------------------------- +@roff_tcache@.It Sy "arenas.nhbins (unsigned) r-" +@roff_tcache@.Bd -ragged -offset indent -compact +@roff_tcache@Total number of thread cache bin size classes. +@roff_tcache@.Ed +.\"----------------------------------------------------------------------------- .It Sy "arenas.bin.<i>.size (size_t) r-" .Bd -ragged -offset indent -compact Maximum size supported by size class. @@ -1147,26 +1121,6 @@ has not been called. @roff_stats@Cumulative number of small allocation requests. @roff_stats@.Ed .\"----------------------------------------------------------------------------- -@roff_stats@.It Sy "stats.arenas.<i>.medium.allocated (size_t) r-" -@roff_stats@.Bd -ragged -offset indent -compact -@roff_stats@Number of bytes currently allocated by medium objects. -@roff_stats@.Ed -.\"----------------------------------------------------------------------------- -@roff_stats@.It Sy "stats.arenas.<i>.medium.nmalloc (uint64_t) r-" -@roff_stats@.Bd -ragged -offset indent -compact -@roff_stats@Cumulative number of allocation requests served by medium bins. -@roff_stats@.Ed -.\"----------------------------------------------------------------------------- -@roff_stats@.It Sy "stats.arenas.<i>.medium.ndalloc (uint64_t) r-" -@roff_stats@.Bd -ragged -offset indent -compact -@roff_stats@Cumulative number of medium objects returned to bins. -@roff_stats@.Ed -.\"----------------------------------------------------------------------------- -@roff_stats@.It Sy "stats.arenas.<i>.medium.nrequests (uint64_t) r-" -@roff_stats@.Bd -ragged -offset indent -compact -@roff_stats@Cumulative number of medium allocation requests. -@roff_stats@.Ed -.\"----------------------------------------------------------------------------- @roff_stats@.It Sy "stats.arenas.<i>.large.allocated (size_t) r-" @roff_stats@.Bd -ragged -offset indent -compact @roff_stats@Number of bytes currently allocated by large objects. @@ -1174,12 +1128,19 @@ has not been called. .\"----------------------------------------------------------------------------- @roff_stats@.It Sy "stats.arenas.<i>.large.nmalloc (uint64_t) r-" @roff_stats@.Bd -ragged -offset indent -compact -@roff_stats@Cumulative number of large allocation requests. +@roff_stats@Cumulative number of large allocation requests served directly by +@roff_stats@the arena. @roff_stats@.Ed .\"----------------------------------------------------------------------------- @roff_stats@.It Sy "stats.arenas.<i>.large.ndalloc (uint64_t) r-" @roff_stats@.Bd -ragged -offset indent -compact -@roff_stats@Cumulative number of large deallocation requests. +@roff_stats@Cumulative number of large deallocation requests served directly by +@roff_stats@the arena. +@roff_stats@.Ed +.\"----------------------------------------------------------------------------- +@roff_stats@.It Sy "stats.arenas.<i>.large.nrequests (uint64_t) r-" +@roff_stats@.Bd -ragged -offset indent -compact +@roff_stats@Cumulative number of large allocation requests. @roff_stats@.Ed .\"----------------------------------------------------------------------------- @roff_stats@.It Sy "stats.arenas.<i>.bins.<j>.allocated (size_t) r-" @@ -1233,6 +1194,18 @@ has not been called. @roff_stats@Current number of runs. @roff_stats@.Ed .\"----------------------------------------------------------------------------- +@roff_stats@.It Sy "stats.arenas.<i>.lruns.<j>.nmalloc (uint64_t) r-" +@roff_stats@.Bd -ragged -offset indent -compact +@roff_stats@Cumulative number of allocation requests for this size class served +@roff_stats@directly by the arena. +@roff_stats@.Ed +.\"----------------------------------------------------------------------------- +@roff_stats@.It Sy "stats.arenas.<i>.lruns.<j>.ndalloc (uint64_t) r-" +@roff_stats@.Bd -ragged -offset indent -compact +@roff_stats@Cumulative number of deallocation requests for this size class +@roff_stats@served directly by the arena. +@roff_stats@.Ed +.\"----------------------------------------------------------------------------- @roff_stats@.It Sy "stats.arenas.<i>.lruns.<j>.nrequests (uint64_t) r-" @roff_stats@.Bd -ragged -offset indent -compact @roff_stats@Cumulative number of allocation requests for this size class. |