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  1. 24 9月, 2013 8 次提交
    • K
      rcu: Fix CONFIG_RCU_NOCB_CPU_ALL panic on machines with sparse CPU mask · 5d5a0800
      由 Kirill Tkhai 提交于 
      Some architectures have sparse cpu mask. UltraSparc's cpuinfo for example:

CPU0: online
CPU2: online

So, set only possible CPUs when CONFIG_RCU_NOCB_CPU_ALL is enabled.

Also, check that user passes right 'rcu_nocbs=' option.
Signed-off-by: NKirill Tkhai <tkhai@yandex.ru>
CC: Dipankar Sarma <dipankar@in.ibm.com>
[ paulmck: Fix pr_info() issue noted by scripts/checkpatch.pl. ]
Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
      5d5a0800
    • P
      rcu: Have rcutiny tracepoints use tracepoint_string() · 0d752924
      由 Paul E. McKenney 提交于 
      This commit extends the work done in f7f7bac9 (rcu: Have the RCU
tracepoints use the tracepoint_string infrastructure) to cover rcutiny.
Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
      0d752924
    • P
      rcu: Reject memory-order-induced stall-warning false positives · 26cdfedf
      由 Paul E. McKenney 提交于 
      If a system is idle from an RCU perspective for longer than specified
by CONFIG_RCU_CPU_STALL_TIMEOUT, and if one CPU starts a grace period
just as a second checks for CPU stalls, and if this second CPU happens
to see the old value of rsp->jiffies_stall, it will incorrectly report a
CPU stall.  This is quite rare, but apparently occurs deterministically
on systems with about 6TB of memory.

This commit therefore orders accesses to the data used to determine
whether or not a CPU stall is in progress.  Grace-period initialization
and cleanup first increments rsp->completed to mark the end of the
previous grace period, then records the current jiffies in rsp->gp_start,
then records the jiffies at which a stall can be expected to occur in
rsp->jiffies_stall, and finally increments rsp->gpnum to mark the start
of the new grace period.  Now, this ordering by itself does not prevent
false positives.  For example, if grace-period initialization was delayed
between recording rsp->gp_start and rsp->jiffies_stall, the CPU stall
warning code might still see an old value of rsp->jiffies_stall.

Therefore, this commit also orders the CPU stall warning accesses as
well, loading rsp->gpnum and jiffies, then rsp->jiffies_stall, then
rsp->gp_start, and finally rsp->completed.  This ordering means that
the false-positive scenario in the previous paragraph would result
in rsp->completed being greater than or equal to rsp->gpnum, which is
never valid for a CPU stall, allowing the false positive to be rejected.
Furthermore, any fetch that gets an old value of rsp->jiffies_stall
must also get an old value of rsp->gpnum, which will again be rejected
by the comparison of rsp->gpnum and rsp->completed.  Situations where
rsp->gp_start is later than rsp->jiffies_stall are also rejected, as
are situations where jiffies is less than rsp->jiffies_stall.

Although use of unsynchronized accesses means that there are likely
still some false-positive scenarios (synchronization has proven to be
a very bad idea on large systems), this should get rid of a large class
of these scenarios.
Reported-by: NFabian Herschel <fabian.herschel@suse.com>
Reported-by: NMichal Hocko <mhocko@suse.com>
Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: NMichal Hocko <mhocko@suse.cz>
Tested-by: NJochen Striepe <jochen@tolot.escape.de>
      26cdfedf
    • P
      rcu: Micro-optimize rcu_cpu_has_callbacks() · 69c8d28c
      由 Paul E. McKenney 提交于 
      The for_each_rcu_flavor() loop unconditionally scans all flavors, even
when the first flavor might have some non-lazy callbacks.  Once the
loop has seen a non-lazy callback, further passes through the loop
cannot change the state.  This is not a huge problem, given that there
can be at most three RCU flavors (RCU-bh, RCU-preempt, and RCU-sched),
but this code is on the path to idle, so speeding it up even a small
amount would have some benefit.

This commit therefore does two things:

1.	Rearranges the order of the list of RCU flavors in order to
	place the most active flavor first in the list.  The most active
	RCU flavor is RCU-preempt, or, if there is no RCU-preempt,
	RCU-sched.

2.	Reworks the for_each_rcu_flavor() to exit early when the first
	non-lazy callback is seen, or, in the case where the caller
	does not care about non-lazy callbacks (RCU_FAST_NO_HZ=n),
	when the first callback is seen.
Reported-by: NChen Gang <gang.chen@asianux.com>
Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
      69c8d28c
    • P
      rcu: Silence unused-variable warnings · 289828e6
      由 Paul E. McKenney 提交于 
      The "idle" variable in both rcu_eqs_enter_common() and
rcu_eqs_exit_common() is only used in a WARN_ON_ONCE().  If the kernel
is built disabling WARN_ON_ONCE(), the compiler will complain (rightly)
that "idle" is unused.  This commit therefore adds a __maybe_unused to
the declaration of both variables.
Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
      289828e6
    • C
      rcu: Replace __get_cpu_var() uses · c9d4b0af
      由 Christoph Lameter 提交于 
      __get_cpu_var() is used for multiple purposes in the kernel source. One
of them is address calculation via the form &__get_cpu_var(x). This
calculates the address for the instance of the percpu variable of the
current processor based on an offset.

Other use cases are for storing and retrieving data from the current
processors percpu area.  __get_cpu_var() can be used as an lvalue when
writing data or on the right side of an assignment.

__get_cpu_var() is defined as :

__get_cpu_var() always only does an address determination. However,
store and retrieve operations could use a segment prefix (or global
register on other platforms) to avoid the address calculation.

this_cpu_write() and this_cpu_read() can directly take an offset into
a percpu area and use optimized assembly code to read and write per
cpu variables.

This patch converts __get_cpu_var into either an explicit address
calculation using this_cpu_ptr() or into a use of this_cpu operations
that use the offset. Thereby address calcualtions are avoided and less
registers are used when code is generated.

At the end of the patchset all uses of __get_cpu_var have been removed
so the macro is removed too.

The patchset includes passes over all arches as well. Once these
operations are used throughout then specialized macros can be defined in
non -x86 arches as well in order to optimize per cpu access by f.e. using
a global register that may be set to the per cpu base.

Transformations done to __get_cpu_var()

1. Determine the address of the percpu instance of the current processor.

	DEFINE_PER_CPU(int, y);
	int *x = &__get_cpu_var(y);

    Converts to

	int *x = this_cpu_ptr(&y);

2. Same as #1 but this time an array structure is involved.

	DEFINE_PER_CPU(int, y[20]);
	int *x = __get_cpu_var(y);

    Converts to

	int *x = this_cpu_ptr(y);

3. Retrieve the content of the current processors instance of a per cpu
   variable.

	DEFINE_PER_CPU(int, u);
	int x = __get_cpu_var(y)

   Converts to

	int x = __this_cpu_read(y);

4. Retrieve the content of a percpu struct

	DEFINE_PER_CPU(struct mystruct, y);
	struct mystruct x = __get_cpu_var(y);

   Converts to

	memcpy(this_cpu_ptr(&x), y, sizeof(x));

5. Assignment to a per cpu variable

	DEFINE_PER_CPU(int, y)
	__get_cpu_var(y) = x;

   Converts to

	this_cpu_write(y, x);

6. Increment/Decrement etc of a per cpu variable

	DEFINE_PER_CPU(int, y);
	__get_cpu_var(y)++

   Converts to

	this_cpu_inc(y)
Signed-off-by: NChristoph Lameter <cl@linux.com>
[ paulmck: Address conflicts. ]
Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
      c9d4b0af
    • P
      rcu: Fix dubious "if" condition in __call_rcu_nocb_enqueue() · 829511d8
      由 Paul E. McKenney 提交于 
      This commit replaces an incorrect (but fortunately functional)
bitwise OR ("|") operator with the correct logical OR ("||").
Reported-by: Nkbuild test robot <fengguang.wu@intel.com>
Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
      829511d8
    • P
      rcu: Convert local functions to static · 01896f7e
      由 Paul E. McKenney 提交于 
      The rcu_cpu_stall_timeout kernel parameter, the rcu_dynticks per-CPU
variable, and the rcu_gp_fqs() function are used only locally.  This
commit therefore marks them as static.
Reported-by: Nkbuild test robot <fengguang.wu@intel.com>
Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
      01896f7e
  3. 21 9月, 2013 1 次提交
  5. 13 9月, 2013 5 次提交
  7. 12 9月, 2013 23 次提交
  9. 11 9月, 2013 2 次提交
    • A
      perf: Fix up MMAP2 buffer space reservation · d008d525
      由 Arnaldo Carvalho de Melo 提交于 
      The ino_generation field was added in the PERF_RECORD_MMAP2 record in
the 13d7a241 cset but no space for it was allocated, corrupting the
PERF_FORMAT_{TIME,CPU,TID,etc} area (sample_type/sample_id_all), fix it.

Detected with one of the regression tests done by 'perf test':

  [root@sandy ~]# perf test -v 7
   7: Validate PERF_RECORD_* events & perf_sample fields     :
  --- start ---
  61315294449606 0 PERF_RECORD_SAMPLE
  61315294453161 0 PERF_RECORD_SAMPLE
  61315294454441 0 PERF_RECORD_SAMPLE
  61315294455709 0 PERF_RECORD_SAMPLE
  61315295600899 0 PERF_RECORD_COMM: sleep:6500
  27917287430500 342521613 PERF_RECORD_MMAP2 6500/6500: [0x400000(0x7000) @ 0 00:1d 311442 9016]: /usr/bin/sleep
  MMAP2 going backwards in time, prev=61315295600899, curr=27917287430500
  MMAP2 with unexpected cpu, expected 0, got 342521613
  MMAP2 with unexpected pid, expected 6500, got 1701606191
  MMAP2 with unexpected tid, expected 6500, got 28773
  27917287430500 342561333 PERF_RECORD_MMAP2 6500/6500: [0x3b7e000000(0x223000) @ 0 00:1d 309186 9016]: /usr/lib64/ld-2.16.so
  MMAP2 with unexpected cpu, expected 0, got 342561333
  MMAP2 with unexpected pid, expected 6500, got 1932408369
  MMAP2 with unexpected tid, expected 6500, got 111
  27917287430500 342600095 PERF_RECORD_MMAP2 6500/6500: [0x7fffbd7dc000(0x1000) @ 0x7fffbd7dc000 00:00 0 0]: [vdso]
  MMAP2 with unexpected cpu, expected 0, got 342600095
  MMAP2 with unexpected pid, expected 6500, got 1935963739
  MMAP2 with unexpected tid, expected 6500, got 23919
  27917287430500 342882834 PERF_RECORD_MMAP2 6500/6500: [0x3b7e400000(0x3b8000) @ 0 00:1d 309187 9016]: /usr/lib64/libc-2.16.so
  MMAP2 with unexpected cpu, expected 0, got 342882834
  MMAP2 with unexpected pid, expected 6500, got 909192754
  MMAP2 with unexpected tid, expected 6500, got 7303982
  61316297195411 0 PERF_RECORD_EXIT(6500:6500):(6500:6500)
  ---- end ----
  Validate PERF_RECORD_* events & perf_sample fields: FAILED!
  [root@sandy ~]#

After this patch:

  [root@sandy ~]# perf test 7
   7: Validate PERF_RECORD_* events & perf_sample fields     : Ok
  [root@sandy ~]#
Acked-by: NPeter Zijlstra <peterz@infradead.org>
Acked-by: NStephane Eranian <eranian@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-heeuv986b8ha7whqg4o3he7c@git.kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>
      d008d525
    • G
      fs: bump inode and dentry counters to long · 3942c07c
      由 Glauber Costa 提交于 
      This series reworks our current object cache shrinking infrastructure in
two main ways:

 * Noticing that a lot of users copy and paste their own version of LRU
   lists for objects, we put some effort in providing a generic version.
   It is modeled after the filesystem users: dentries, inodes, and xfs
   (for various tasks), but we expect that other users could benefit in
   the near future with little or no modification.  Let us know if you
   have any issues.

 * The underlying list_lru being proposed automatically and
   transparently keeps the elements in per-node lists, and is able to
   manipulate the node lists individually.  Given this infrastructure, we
   are able to modify the up-to-now hammer called shrink_slab to proceed
   with node-reclaim instead of always searching memory from all over like
   it has been doing.

Per-node lru lists are also expected to lead to less contention in the lru
locks on multi-node scans, since we are now no longer fighting for a
global lock.  The locks usually disappear from the profilers with this
change.

Although we have no official benchmarks for this version - be our guest to
independently evaluate this - earlier versions of this series were
performance tested (details at
http://permalink.gmane.org/gmane.linux.kernel.mm/100537) yielding no
visible performance regressions while yielding a better qualitative
behavior in NUMA machines.

With this infrastructure in place, we can use the list_lru entry point to
provide memcg isolation and per-memcg targeted reclaim.  Historically,
those two pieces of work have been posted together.  This version presents
only the infrastructure work, deferring the memcg work for a later time,
so we can focus on getting this part tested.  You can see more about the
history of such work at http://lwn.net/Articles/552769/

Dave Chinner (18):
  dcache: convert dentry_stat.nr_unused to per-cpu counters
  dentry: move to per-sb LRU locks
  dcache: remove dentries from LRU before putting on dispose list
  mm: new shrinker API
  shrinker: convert superblock shrinkers to new API
  list: add a new LRU list type
  inode: convert inode lru list to generic lru list code.
  dcache: convert to use new lru list infrastructure
  list_lru: per-node list infrastructure
  shrinker: add node awareness
  fs: convert inode and dentry shrinking to be node aware
  xfs: convert buftarg LRU to generic code
  xfs: rework buffer dispose list tracking
  xfs: convert dquot cache lru to list_lru
  fs: convert fs shrinkers to new scan/count API
  drivers: convert shrinkers to new count/scan API
  shrinker: convert remaining shrinkers to count/scan API
  shrinker: Kill old ->shrink API.

Glauber Costa (7):
  fs: bump inode and dentry counters to long
  super: fix calculation of shrinkable objects for small numbers
  list_lru: per-node API
  vmscan: per-node deferred work
  i915: bail out earlier when shrinker cannot acquire mutex
  hugepage: convert huge zero page shrinker to new shrinker API
  list_lru: dynamically adjust node arrays

This patch:

There are situations in very large machines in which we can have a large
quantity of dirty inodes, unused dentries, etc.  This is particularly true
when umounting a filesystem, where eventually since every live object will
eventually be discarded.

Dave Chinner reported a problem with this while experimenting with the
shrinker revamp patchset.  So we believe it is time for a change.  This
patch just moves int to longs.  Machines where it matters should have a
big long anyway.
Signed-off-by: NGlauber Costa <glommer@openvz.org>
Cc: Dave Chinner <dchinner@redhat.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Cc: Arve Hjønnevåg <arve@android.com>
Cc: Carlos Maiolino <cmaiolino@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Chuck Lever <chuck.lever@oracle.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Dave Chinner <dchinner@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Gleb Natapov <gleb@redhat.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: J. Bruce Fields <bfields@redhat.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Kent Overstreet <koverstreet@google.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Steven Whitehouse <swhiteho@redhat.com>
Cc: Thomas Hellstrom <thellstrom@vmware.com>
Cc: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
      3942c07c
  11. 10 9月, 2013 1 次提交