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mmap updates/refactoring

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This commit is contained in:
Christian Thaeter 2008-12-08 20:57:57 +01:00
parent 9f497cdaa3
commit db202e298e
5 changed files with 77 additions and 59 deletions
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87
src/backend/mmap.c
View file

@ -27,6 +27,7 @@
#include <unistd.h>
#include <sys/mman.h>
#include <errno.h>
/**
* @file
@ -48,14 +49,12 @@ LUMIERA_ERROR_DEFINE (MMAP_SPACE, "Address space exhausted");
LumieraMMap
lumiera_mmap_init (LumieraMMap self, LumieraFile file, LList acquirer, off_t start, size_t size, size_t chunksize)
lumiera_mmap_init (LumieraMMap self, LumieraFile file, off_t start, size_t size)
{
TRACE (mmap);
REQUIRE (self);
REQUIRE (file);
REQUIRE (acquirer);
REQUIRE (llist_is_empty (acquirer));
REQUIRE (start >= 0);
REQUIRE (size);
@ -85,9 +84,10 @@ lumiera_mmap_init (LumieraMMap self, LumieraFile file, LList acquirer, off_t sta
if (fd == -1)
goto efile;
void* addr = NULL;
void* addr = (void*)-1;
off_t begin = 0;
size_t length = 0;
size_t chunksize = lumiera_file_chunksize_get (file);
/**
* Maintaining the right[tm] mmaping size is a bit tricky:
@ -99,31 +99,35 @@ lumiera_mmap_init (LumieraMMap self, LumieraFile file, LList acquirer, off_t sta
* - Requests beyond the file end must ftruncate and map additional pages
* - Create the 'refmap' which contains a refounter per chunk
**/
while (!addr)
/**
* Recovering address space strategies:
* mmap() will fail when too much memory got mmaped after some time which is then
* recovered in the following way
* 1. create a new mmap while the cachelimit is not reached.
* 2. All unused mmaps are kept in a mrucache, drop the oldest one.
* mmap() still fails..
* 3.a When the intented mmaping size is the same as mmap_window_size then reduce (/2) the window size and retry.
* 3.b When the intented mmaping size was biggier than mmap_window_size then free more mmaps from the cache.
* 4 When the cache is empty (that means all mmaps in use), scan the mmaps in use if they can be reduced
* mmap_window_size is already reduced now (half of refmap free from either end)
**/
enum {
FIRST_TRY,
DROP_FROM_CACHE,
REDUCE_WINDOW,
REDUCE_IN_USE,
GIVE_UP
} strategy = FIRST_TRY;
while (addr == (void*)-1)
{
/**
* Recovering address space strategies:
* mmap() will fail when too much memory got mmaped after some time which is then
* recovered in the following way
* 1. create a new mmap while the cachelimit is not reached.
* 2. All unused mmaps are kept in a mrucache, drop the oldest one.
* mmap() still fails..
* 3.a When the intented mmaping size is the same as mmap_window_size then reduce (/2) the window size and retry.
* 3.b When the intented mmaping size was biggier than mmap_window_size then free more mmaps from the cache.
* 4 When the cache is empty (that means all mmaps in use), scan the mmaps in use if they can be reduced
* mmap_window_size is already reduced now (half of refmap free from either end)
**/
enum {
FIRST_TRY,
DROP_FROM_CACHE,
REDUCE_WINDOW,
REDUCE_IN_USE,
GIVE_UP
} strategy = FIRST_TRY;
TODO ("check if current mmaped size exceeds configured as_size (as_size be smaller than retrieved from getrlimit())");
switch (strategy++)
{
case FIRST_TRY:
TRACE (mmap, "FIRST_TRY");
/* align begin and end to chunk boundaries */
begin = start & ~(chunksize-1);
length = ((start+size+chunksize-1) & ~(chunksize-1)) - begin;
@ -142,18 +146,15 @@ lumiera_mmap_init (LumieraMMap self, LumieraFile file, LList acquirer, off_t sta
descriptor->stat.st_size = begin+length;
descriptor->realsize = start+size;
}
else
{
LUMIERA_ERROR_SET (mmap, MMAP_NWRITE);
goto ewrite;
}
}
else if (length < (size_t)mmap_window_size)
length = mmap_window_size;
if ((descriptor->flags & O_ACCMODE) == O_RDONLY)
/* The last mmaped chunk of a file can be as small as possible when the file is readonly */
length = start+size - begin;
{
/* The last mmaped chunk of a file can be as small as possible when the file is readonly */
length = start+size - begin;
}
break;
case DROP_FROM_CACHE:
@ -182,6 +183,9 @@ lumiera_mmap_init (LumieraMMap self, LumieraFile file, LList acquirer, off_t sta
MAP_SHARED,
fd,
begin);
INFO_IF (addr==(void*)-1, mmap, "mmap failed %s", strerror (errno));
ENSURE (errno == 0 || errno == ENOMEM, "unexpected mmap error %s", strerror (errno));
}
llist_init (&self->cachenode);
@ -190,11 +194,8 @@ lumiera_mmap_init (LumieraMMap self, LumieraFile file, LList acquirer, off_t sta
self->start = begin;
self->size = length;
self->address = addr;
self->refmap = lumiera_calloc (length/chunksize, sizeof (unsigned short));
llist_insert_head (&self->cachenode, acquirer);
self->refmap = lumiera_calloc ((length-1)/chunksize+1, sizeof (unsigned short));
self->refcnt = 1;
lumiera_mmapcache_announce (lumiera_mcache, self);
lumiera_file_handle_release (file);
@ -202,7 +203,6 @@ lumiera_mmap_init (LumieraMMap self, LumieraFile file, LList acquirer, off_t sta
espace:
etruncate:
ewrite:
efile:
lumiera_file_handle_release (file);
lumiera_free (self);
@ -210,17 +210,17 @@ lumiera_mmap_init (LumieraMMap self, LumieraFile file, LList acquirer, off_t sta
}
LumieraMMap
lumiera_mmap_new (LumieraFile file, LList acquirer, off_t start, size_t size, size_t chunksize)
lumiera_mmap_new (LumieraFile file, off_t start, size_t size)
{
TRACE (mmap);
LumieraMMap self = lumiera_mmapcache_mmap_acquire (lumiera_mcache);
if (lumiera_mmap_init (self, file, acquirer, start, size, chunksize))
if (lumiera_mmap_init (self, file, start, size))
return self;
else
{
free (self);
lumiera_free (self);
return NULL;
}
}
@ -237,9 +237,10 @@ lumiera_mmap_delete (LumieraMMap self)
/* The matching mappings->lock must be hold or being unrelevant (mappings destructor) here, we can't asset this from here, good luck */
llist_unlink (&self->searchnode);
TRACE (mmap, "unmap at %p with size %zd", self->address, self->size);
munmap (self->address, self->size);
free (self->refmap);
free (self);
lumiera_free (self->refmap);
lumiera_free (self);
}
}
@ -256,7 +257,7 @@ lumiera_mmap_destroy_node (LList node)
llist_unlink (&self->searchnode); TODO ("must lock mmapings -> deadlock");
munmap (self->address, self->size);
free (self->refmap);
lumiera_free (self->refmap);
return self;
}

17
src/backend/mmap.h
View file

@ -29,6 +29,7 @@ typedef struct lumiera_mmap_struct lumiera_mmap;
typedef lumiera_mmap* LumieraMMap;
#include "backend/file.h"
#include "backend/filedescriptor.h"
@ -61,17 +62,27 @@ struct lumiera_mmap_struct
size_t size;
void* address;
/** accumulated references, this is 0 when checked into the cache **/
unsigned long refcnt;
/** array with refcounters per chunk **/
unsigned short* refmap;
unsigned short* refmap; // TODO flexible array?
};
LumieraMMap
lumiera_mmap_init (LumieraMMap self, LumieraFile file, LList acquirer, off_t start, size_t size, size_t chunksize);
lumiera_mmap_init (LumieraMMap self, LumieraFile file, off_t start, size_t size);
LumieraMMap
lumiera_mmap_new (LumieraFile file, LList acquirer, off_t start, size_t size, size_t chunksize);
lumiera_mmap_new (LumieraFile file, off_t start, size_t size);
static inline void*
lumiera_mmap_address (LumieraMMap self)
{
return self->address;
}
void

2
src/backend/mmapcache.c
View file

@ -138,6 +138,7 @@ lumiera_mmapcache_checkout (LumieraMMapcache self, LumieraMMap handle)
{
TODO ("cached stats");
lumiera_mrucache_checkout (&self->cache, &handle->cachenode);
++handle->refcnt;
}
return handle;
@ -152,6 +153,7 @@ lumiera_mmapcache_checkin (LumieraMMapcache self, LumieraMMap handle)
LUMIERA_MUTEX_SECTION (mmapcache, &self->lock)
{
TODO ("cached stats");
--handle->refcnt;
lumiera_mrucache_checkin (&self->cache, &handle->cachenode);
}
}

29
src/backend/mmapings.c
View file

@ -95,9 +95,11 @@ lumiera_mmapings_mmap_acquire (LumieraMMapings self, LumieraFile file, LList acq
{
REQUIRE (llist_is_empty (acquirer));
/* find best matching mmap, crude way */
/* find first matching mmap, crude way */
LLIST_FOREACH (&self->mmaps, node)
{
TODO ("improve this selection algorithm, choose mmaps by size, move mfu to head etc");
LumieraMMap mmap = LLIST_TO_STRUCTP (node, lumiera_mmap, searchnode);
if (mmap->size >= size && mmap->start <= start && mmap->start+mmap->size >= start+size)
@ -107,24 +109,25 @@ lumiera_mmapings_mmap_acquire (LumieraMMapings self, LumieraFile file, LList acq
}
}
if (!ret)
/* found? */
if (ret)
{
/* create new mmap */
TRACE (mmapings, "mmap not found, creating", mmap);
ret = lumiera_mmap_new (file, acquirer, start, size, self->chunksize);
llist_insert_head (&self->mmaps, &ret->searchnode);
TODO ("sort search list");
if (!ret->refcnt)
/* in cache, needs to me checked out */
lumiera_mmapcache_checkout (lumiera_mcache, ret);
}
else
{
/* found mmap */
/* create new mmap */
TRACE (mmapings, "mmap not found, creating", mmap);
ret = lumiera_mmap_new (file, start, size);
UNIMPLEMENTED ("reuse existing mmap");
//lumiera_mmapcache_checkout (lumiera_mcache, self);
// checkout add acquirer
llist_insert_head (&self->mmaps, &ret->searchnode);
TODO ("sort search list?");
}
llist_insert_head (&ret->cachenode, acquirer);
}
return ret;

1
src/backend/mmapings.h
View file

@ -30,6 +30,7 @@ typedef lumiera_mmapings* LumieraMMapings;
#include "backend/filedescriptor.h"
#include "backend/mmap.h"
#include "backend/file.h"
#include <nobug.h>