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Remove global memory variables
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Platforms such as Illumos and FreeBSD have historically provided
global variables which summerize the memory state of a system.
Linux on the otherhand doesn't expose any of this information
to kernel modules and uses entirely different mechanisms for
memory management.

In order to simplify the original ZFS port to Linux these global
variables were emulated by the SPL for the benefit of ZFS.  As ZoL
has matured over the years it has moved steadily away from these
interfaces and now no longer depends on them at all.

Therefore, this patch completely removes the global variables
availrmem, minfree, desfree, lotsfree, needfree, swapfs_minfree,
and swapfs_reserve.  This greatly simplifies the memory management
code and eliminates a common area of confusion.

Signed-off-by: Brian Behlendorf <[email protected]>
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behlendorf committed Oct 17, 2014
1 parent e1310af commit 8bbbe46
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321 changes: 0 additions & 321 deletions config/spl-build.m4
View file
Original file line number Diff line number Diff line change
Expand Up @@ -29,16 +29,6 @@ AC_DEFUN([SPL_AC_CONFIG_KERNEL], [
SPL_AC_MUTEX_OWNER
SPL_AC_MUTEX_OWNER_TASK_STRUCT
SPL_AC_KALLSYMS_LOOKUP_NAME
SPL_AC_PGDAT_HELPERS
SPL_AC_FIRST_ONLINE_PGDAT
SPL_AC_NEXT_ONLINE_PGDAT
SPL_AC_NEXT_ZONE
SPL_AC_PGDAT_LIST
SPL_AC_GLOBAL_PAGE_STATE
SPL_AC_ZONE_STAT_ITEM_FREE
SPL_AC_ZONE_STAT_ITEM_INACTIVE
SPL_AC_ZONE_STAT_ITEM_ACTIVE
SPL_AC_GET_ZONE_COUNTS
SPL_AC_USER_PATH_DIR
SPL_AC_SET_FS_PWD
SPL_AC_SET_FS_PWD_WITH_CONST
Expand Down Expand Up @@ -1006,317 +996,6 @@ AC_DEFUN([SPL_AC_PDE_DATA], [
])
])

dnl #
dnl # 2.6.17 API change
dnl # The helper functions first_online_pgdat(), next_online_pgdat(), and
dnl # next_zone() are introduced to simplify for_each_zone(). These symbols
dnl # were exported in 2.6.17 for use by modules which was consistent with
dnl # the previous implementation of for_each_zone(). From 2.6.18 - 2.6.19
dnl # the symbols were exported as 'unused', and by 2.6.20 they exports
dnl # were dropped entirely leaving modules no way to directly iterate over
dnl # the zone list. Because we need access to the zone helpers we check
dnl # if the kernel contains the old or new implementation. Then we check
dnl # to see if the symbols we need for each version are available. If they
dnl # are not, dynamically aquire the addresses with kallsyms_lookup_name().
dnl #
AC_DEFUN([SPL_AC_PGDAT_HELPERS], [
AC_MSG_CHECKING([whether symbol *_pgdat exist])
grep -q -E 'first_online_pgdat' $LINUX/include/linux/mmzone.h 2>/dev/null
rc=$?
if test $rc -eq 0; then
AC_MSG_RESULT([yes])
AC_DEFINE(HAVE_PGDAT_HELPERS, 1, [pgdat helpers are available])
else
AC_MSG_RESULT([no])
fi
])

dnl #
dnl # Proposed API change,
dnl # This symbol is not available in stock kernels. You may build a
dnl # custom kernel with the *-spl-export-symbols.patch which will export
dnl # these symbols for use. If your already rolling a custom kernel for
dnl # your environment this is recommended.
dnl #
AC_DEFUN([SPL_AC_FIRST_ONLINE_PGDAT],
[AC_MSG_CHECKING([whether first_online_pgdat() is available])
SPL_LINUX_TRY_COMPILE_SYMBOL([
#include <linux/mmzone.h>
], [
first_online_pgdat();
], [first_online_pgdat], [], [
AC_MSG_RESULT(yes)
AC_DEFINE(HAVE_FIRST_ONLINE_PGDAT, 1,
[first_online_pgdat() is available])
], [
AC_MSG_RESULT(no)
])
])

dnl #
dnl # Proposed API change,
dnl # This symbol is not available in stock kernels. You may build a
dnl # custom kernel with the *-spl-export-symbols.patch which will export
dnl # these symbols for use. If your already rolling a custom kernel for
dnl # your environment this is recommended.
dnl #
AC_DEFUN([SPL_AC_NEXT_ONLINE_PGDAT],
[AC_MSG_CHECKING([whether next_online_pgdat() is available])
SPL_LINUX_TRY_COMPILE_SYMBOL([
#include <linux/mmzone.h>
], [
next_online_pgdat(NULL);
], [next_online_pgdat], [], [
AC_MSG_RESULT(yes)
AC_DEFINE(HAVE_NEXT_ONLINE_PGDAT, 1,
[next_online_pgdat() is available])
], [
AC_MSG_RESULT(no)
])
])

dnl #
dnl # Proposed API change,
dnl # This symbol is not available in stock kernels. You may build a
dnl # custom kernel with the *-spl-export-symbols.patch which will export
dnl # these symbols for use. If your already rolling a custom kernel for
dnl # your environment this is recommended.
dnl #
AC_DEFUN([SPL_AC_NEXT_ZONE],
[AC_MSG_CHECKING([whether next_zone() is available])
SPL_LINUX_TRY_COMPILE_SYMBOL([
#include <linux/mmzone.h>
], [
next_zone(NULL);
], [next_zone], [], [
AC_MSG_RESULT(yes)
AC_DEFINE(HAVE_NEXT_ZONE, 1, [next_zone() is available])
], [
AC_MSG_RESULT(no)
])
])

dnl #
dnl # 2.6.17 API change,
dnl # See SPL_AC_PGDAT_HELPERS for details.
dnl #
AC_DEFUN([SPL_AC_PGDAT_LIST],
[AC_MSG_CHECKING([whether pgdat_list is available])
SPL_LINUX_TRY_COMPILE_SYMBOL([
#include <linux/topology.h>
pg_data_t *tmp = pgdat_list;
], [], [pgdat_list], [], [
AC_MSG_RESULT(yes)
AC_DEFINE(HAVE_PGDAT_LIST, 1, [pgdat_list is available])
], [
AC_MSG_RESULT(no)
])
])

dnl #
dnl # 2.6.18 API change,
dnl # First introduced global_page_state() support as an inline.
dnl #
AC_DEFUN([SPL_AC_GLOBAL_PAGE_STATE], [
AC_MSG_CHECKING([whether global_page_state() is available])
SPL_LINUX_TRY_COMPILE([
#include <linux/mm.h>
],[
unsigned long state __attribute__ ((unused));
state = global_page_state(0);
],[
AC_MSG_RESULT(yes)
AC_DEFINE(HAVE_GLOBAL_PAGE_STATE, 1,
[global_page_state() is available])
],[
AC_MSG_RESULT(no)
])
])

dnl #
dnl # 2.6.21 API change (plus subsequent naming convention changes),
dnl # Public global zone stats now include a free page count. However
dnl # the enumerated names of the counters have changed since this API
dnl # was introduced. We need to deduce the corrent name to use. This
dnl # replaces the priviate get_zone_counts() interface.
dnl #
dnl # NR_FREE_PAGES was available from 2.6.21 to current kernels, which
dnl # is 2.6.30 as of when this was written.
dnl #
AC_DEFUN([SPL_AC_ZONE_STAT_ITEM_FREE], [
AC_MSG_CHECKING([whether page state NR_FREE_PAGES is available])
SPL_LINUX_TRY_COMPILE([
#include <linux/mm.h>
],[
enum zone_stat_item zsi __attribute__ ((unused));
zsi = NR_FREE_PAGES;
],[
AC_MSG_RESULT(yes)
AC_DEFINE(HAVE_ZONE_STAT_ITEM_NR_FREE_PAGES, 1,
[Page state NR_FREE_PAGES is available])
],[
AC_MSG_RESULT(no)
])
])

dnl #
dnl # 2.6.21 API change (plus subsequent naming convention changes),
dnl # Public global zone stats now include an inactive page count. However
dnl # the enumerated names of the counters have changed since this API
dnl # was introduced. We need to deduce the corrent name to use. This
dnl # replaces the priviate get_zone_counts() interface.
dnl #
dnl # NR_INACTIVE was available from 2.6.21 to 2.6.27 and included both
dnl # anonymous and file inactive pages. As of 2.6.28 it was split in
dnl # to NR_INACTIVE_ANON and NR_INACTIVE_FILE.
dnl #
AC_DEFUN([SPL_AC_ZONE_STAT_ITEM_INACTIVE], [
AC_MSG_CHECKING([whether page state NR_INACTIVE is available])
SPL_LINUX_TRY_COMPILE([
#include <linux/mm.h>
],[
enum zone_stat_item zsi __attribute__ ((unused));
zsi = NR_INACTIVE;
],[
AC_MSG_RESULT(yes)
AC_DEFINE(HAVE_ZONE_STAT_ITEM_NR_INACTIVE, 1,
[Page state NR_INACTIVE is available])
],[
AC_MSG_RESULT(no)
])
AC_MSG_CHECKING([whether page state NR_INACTIVE_ANON is available])
SPL_LINUX_TRY_COMPILE([
#include <linux/mm.h>
],[
enum zone_stat_item zsi __attribute__ ((unused));
zsi = NR_INACTIVE_ANON;
],[
AC_MSG_RESULT(yes)
AC_DEFINE(HAVE_ZONE_STAT_ITEM_NR_INACTIVE_ANON, 1,
[Page state NR_INACTIVE_ANON is available])
],[
AC_MSG_RESULT(no)
])
AC_MSG_CHECKING([whether page state NR_INACTIVE_FILE is available])
SPL_LINUX_TRY_COMPILE([
#include <linux/mm.h>
],[
enum zone_stat_item zsi __attribute__ ((unused));
zsi = NR_INACTIVE_FILE;
],[
AC_MSG_RESULT(yes)
AC_DEFINE(HAVE_ZONE_STAT_ITEM_NR_INACTIVE_FILE, 1,
[Page state NR_INACTIVE_FILE is available])
],[
AC_MSG_RESULT(no)
])
])

dnl #
dnl # 2.6.21 API change (plus subsequent naming convention changes),
dnl # Public global zone stats now include an active page count. However
dnl # the enumerated names of the counters have changed since this API
dnl # was introduced. We need to deduce the corrent name to use. This
dnl # replaces the priviate get_zone_counts() interface.
dnl #
dnl # NR_ACTIVE was available from 2.6.21 to 2.6.27 and included both
dnl # anonymous and file active pages. As of 2.6.28 it was split in
dnl # to NR_ACTIVE_ANON and NR_ACTIVE_FILE.
dnl #
AC_DEFUN([SPL_AC_ZONE_STAT_ITEM_ACTIVE], [
AC_MSG_CHECKING([whether page state NR_ACTIVE is available])
SPL_LINUX_TRY_COMPILE([
#include <linux/mm.h>
],[
enum zone_stat_item zsi __attribute__ ((unused));
zsi = NR_ACTIVE;
],[
AC_MSG_RESULT(yes)
AC_DEFINE(HAVE_ZONE_STAT_ITEM_NR_ACTIVE, 1,
[Page state NR_ACTIVE is available])
],[
AC_MSG_RESULT(no)
])
AC_MSG_CHECKING([whether page state NR_ACTIVE_ANON is available])
SPL_LINUX_TRY_COMPILE([
#include <linux/mm.h>
],[
enum zone_stat_item zsi __attribute__ ((unused));
zsi = NR_ACTIVE_ANON;
],[
AC_MSG_RESULT(yes)
AC_DEFINE(HAVE_ZONE_STAT_ITEM_NR_ACTIVE_ANON, 1,
[Page state NR_ACTIVE_ANON is available])
],[
AC_MSG_RESULT(no)
])
AC_MSG_CHECKING([whether page state NR_ACTIVE_FILE is available])
SPL_LINUX_TRY_COMPILE([
#include <linux/mm.h>
],[
enum zone_stat_item zsi __attribute__ ((unused));
zsi = NR_ACTIVE_FILE;
],[
AC_MSG_RESULT(yes)
AC_DEFINE(HAVE_ZONE_STAT_ITEM_NR_ACTIVE_FILE, 1,
[Page state NR_ACTIVE_FILE is available])
],[
AC_MSG_RESULT(no)
])
])

dnl #
dnl # Proposed API change for legacy kernels.
dnl # This symbol is not available in older kernels. For kernels post
dnl # 2.6.21 the global_page_state() API is used to get free/inactive/active
dnl # page state information. This symbol is only used in legacy kernels
dnl # any only as a last resort.
dnl
AC_DEFUN([SPL_AC_GET_ZONE_COUNTS], [
AC_MSG_CHECKING([whether symbol get_zone_counts is needed])
SPL_LINUX_TRY_COMPILE([
],[
#if !defined(HAVE_ZONE_STAT_ITEM_NR_FREE_PAGES)
#error "global_page_state needs NR_FREE_PAGES"
#endif
#if !defined(HAVE_ZONE_STAT_ITEM_NR_ACTIVE) && \
!defined(HAVE_ZONE_STAT_ITEM_NR_ACTIVE_ANON) && \
!defined(HAVE_ZONE_STAT_ITEM_NR_ACTIVE_FILE)
#error "global_page_state needs NR_ACTIVE*"
#endif
#if !defined(HAVE_ZONE_STAT_ITEM_NR_INACTIVE) && \
!defined(HAVE_ZONE_STAT_ITEM_NR_INACTIVE_ANON) && \
!defined(HAVE_ZONE_STAT_ITEM_NR_INACTIVE_FILE)
#error "global_page_state needs NR_INACTIVE*"
#endif
],[
AC_MSG_RESULT(no)
],[
AC_MSG_RESULT(yes)
AC_DEFINE(NEED_GET_ZONE_COUNTS, 1,
[get_zone_counts() is needed])
AC_MSG_CHECKING([whether get_zone_counts() is available])
SPL_LINUX_TRY_COMPILE_SYMBOL([
#include <linux/mmzone.h>
], [
get_zone_counts(NULL, NULL, NULL);
], [get_zone_counts], [], [
AC_MSG_RESULT(yes)
AC_DEFINE(HAVE_GET_ZONE_COUNTS, 1,
[get_zone_counts() is available])
], [
AC_MSG_RESULT(no)
])
])
])

dnl #
dnl # 2.6.27 API change,
dnl # The user_path_dir() replaces __user_walk()
Expand Down
16 changes: 0 additions & 16 deletions include/linux/mm_compat.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -28,22 +28,6 @@
#include <linux/mm.h>
#include <linux/fs.h>

/*
* Linux 2.6.31 API Change.
* Individual pages_{min,low,high} moved in to watermark array.
*/
#ifndef min_wmark_pages
#define min_wmark_pages(z) (z->pages_min)
#endif

#ifndef low_wmark_pages
#define low_wmark_pages(z) (z->pages_low)
#endif

#ifndef high_wmark_pages
#define high_wmark_pages(z) (z->pages_high)
#endif

#if !defined(HAVE_SHRINK_CONTROL_STRUCT)
struct shrink_control {
gfp_t gfp_mask;
Expand Down
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