- 16 Dec, 2009 40 commits
-
-
Manfred Spraul authored
If multiple simple decrements on the same semaphore are pending, then the current code scans all decrement operations, even if the semaphore value is already 0. The patch optimizes that: if the semaphore value is 0, then there is no need to scan the q->alter entries. Note that this is a common case: It happens if 100 decrements by one are pending and now an increment by one increases the semaphore value from 0 to 1. Without this patch, all 100 entries are scanned. With the patch, only one entry is scanned, then woken up. Then the new rule triggers and the scanning is aborted, without looking at the remaining 99 tasks. With this patch, single sop increment/decrement by 1 are now O(1). (same as with Nick's patch) Signed-off-by:
Manfred Spraul <manfred@colorfullife.com> Cc: Nick Piggin <npiggin@suse.de> Cc: Pierre Peiffer <peifferp@gmail.com> Signed-off-by:
Andrew Morton <akpm@linux-foundation.org> Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org>
-
Manfred Spraul authored
sysv sem has the concept of semaphore arrays that consist out of multiple semaphores. Atomic operations that affect multiple semaphores are supported. The patch optimizes single semaphore operation calls that affect only one semaphore: It's not necessary to scan all pending operations, it is sufficient to scan the per-semaphore list. The idea is from Nick Piggin version of an ipc sem improvement, the implementation is different: The code tries to keep as much common code as possible. As the result, the patch is simpler, but optimizes fewer cases. Signed-off-by:
-
Manfred Spraul authored
Based on Nick's findings: sysv sem has the concept of semaphore arrays that consist out of multiple semaphores. Atomic operations that affect multiple semaphores are supported. The patch is the first step for optimizing simple, single semaphore operations: In addition to the global list of all pending operations, a 2nd, per-semaphore list with the simple operations is added. Note: this patch does not make sense by itself, the new list is used nowhere. Signed-off-by:
-
Manfred Spraul authored
Reduce the amount of scanning of the list of pending semaphore operations: If try_atomic_semop failed, then no changes were applied. Thus no need to restart. Additionally, this patch correct an incorrect comment: It's possible to wait for arbitrary semaphore values (do a dec by <x>, wait-for-zero, inc by <x> in one atomic operation) Both changes are from Nick Piggin, the patch is the result of a different split of the individual changes. Signed-off-by:
-
Nick Piggin authored
The strange sysv semaphore wakeup scheme has a kind of busy-wait lock involved, which could deadlock if preemption is enabled during the "lock". It is an implementation detail (due to a spinlock being held) that this is actually the case. However if "spinlocks" are made preemptible, or if the sem lock is changed to a sleeping lock for example, then the wakeup would become buggy. So this might be a bugfix for -rt kernels. Imagine waker being preempted by wakee and never clearing IN_WAKEUP -- if wakee has higher RT priority then there is a priority inversion deadlock. Even if there is not a priority inversion to cause a deadlock, then there is still time wasted spinning. Signed-off-by:
Nick Piggin <npiggin@suse.de> Signed-off-by:
-
Nick Piggin authored
Replace the handcoded list operations in update_queue() with the standard list_for_each_entry macros. list_for_each_entry_safe() must be used, because list entries can disappear immediately uppon the wakeup event. Signed-off-by:
-
Nick Piggin authored
Around a month ago, there was some discussion about an improvement of the sysv sem algorithm: Most (at least: some important) users only use simple semaphore operations, therefore it's worthwile to optimize this use case. This patch: Move last looked up sem_undo struct to the head of the task's undo list. Attempt to move common entries to the front of the list so search time is reduced. This reduces lookup_undo on oprofile of problematic SAP workload by 30% (see patch 4 for a description of SAP workload). Signed-off-by:
-
Serge E. Hallyn authored
We have apparently had a memory leak since 7ca7e564 "ipc: store ipcs into IDRs" in 2007. The idr of which 3 exist for each ipc namespace is never freed. This patch simply frees them when the ipcns is freed. I don't believe any idr_remove() are done from rcu (and could therefore be delayed until after this idr_destroy()), so the patch should be safe. Some quick testing showed no harm, and the memory leak fixed. Caught by kmemleak. Signed-off-by:
Serge E. Hallyn <serue@us.ibm.com> Signed-off-by:
-
Oleg Nesterov authored
Move the call to do_signal_stop() down, after tracehook call. This makes ->group_stop_count condition visible to tracers before do_signal_stop() will participate in this group-stop. Currently the patch has no effect, tracehook_get_signal() always returns 0. Signed-off-by:
Oleg Nesterov <oleg@redhat.com> Acked-by:
Roland McGrath <roland@redhat.com> Signed-off-by:
-
Oleg Nesterov authored
Kill force_sig_specific(), this trivial wrapper has no callers. Signed-off-by:
-
Oleg Nesterov authored
Trivial, s/0/SI_USER/ in collect_signal() for grep. This is a bit confusing, we don't know the source of this signal. But we don't care, and "info->si_code = 0" is imho worse. Signed-off-by:
-
Oleg Nesterov authored
Change send_signal() to use si_fromuser(). From now SEND_SIG_NOINFO triggers the "from_ancestor_ns" check. This fixes reparent_thread()->group_send_sig_info(pdeath_signal) behaviour, before this patch send_signal() does not detect the cross-namespace case when the child of the dying parent belongs to the sub-namespace. This patch can affect the behaviour of send_sig(), kill_pgrp() and kill_pid() when the caller sends the signal to the sub-namespace with "priv == 0" but surprisingly all callers seem to use them correctly, including disassociate_ctty(on_exit). Except: drivers/staging/comedi/drivers/addi-data/*.c incorrectly use send_sig(priv => 0). But his is minor and should be fixed anyway. Reported-by:
Daniel Lezcano <dlezcano@fr.ibm.com> Signed-off-by:
Sukadev Bhattiprolu <sukadev@us.ibm.com> Signed-off-by:
-
Oleg Nesterov authored
No changes in compiled code. The patch adds the new helper, si_fromuser() and changes check_kill_permission() to use this helper. The real effect of this patch is that from now we "officially" consider SEND_SIG_NOINFO signal as "from user-space" signals. This is already true if we look at the code which uses SEND_SIG_NOINFO, except __send_signal() has another opinion - see the next patch. The naming of these special SEND_SIG_XXX siginfo's is really bad imho. From __send_signal()'s pov they mean SEND_SIG_NOINFO from user SEND_SIG_PRIV from kernel SEND_SIG_FORCED no info Signed-off-by:
-
Oleg Nesterov authored
Suggested by Roland. Unlike powepc, x86 always calls tracehook_report_syscall_exit(step) with step = 0, and sends the trap by hand. This results in unnecessary SIGTRAP when PTRACE_SINGLESTEP follows the syscall-exit stop. Change syscall_trace_leave() to pass the correct "step" argument to tracehook and remove the send_sigtrap() logic. Signed-off-by:
-
Oleg Nesterov authored
Suggested by Roland. Implement user_single_step_siginfo() for x86. Extract this code from send_sigtrap(). Since x86 calls tracehook_report_syscall_exit(step => 0) the new helper is not used yet. Signed-off-by:
-
Oleg Nesterov authored
Suggested by Roland. Change tracehook_report_syscall_exit() to look at step flag and send the trap signal if needed. This change affects ia64, microblaze, parisc, powerpc, sh. They pass nonzero "step" argument to tracehook but since it was ignored the tracee reports via ptrace_notify(), this is not right and not consistent. - PTRACE_SETSIGINFO doesn't work - if the tracer resumes the tracee with signr != 0 the new signal is generated rather than delivering it - If PT_TRACESYSGOOD is set the tracee reports the wrong exit_code I don't have a powerpc machine, but I think this test-case should see the difference: #include <unistd.h> #include <sys/ptrace.h> #include <sys/wait.h> #include <assert.h> #include <stdio.h> int main(void) { int pid, status; if (!(pid = fork())) { assert(ptrace(PTRACE_TRACEME) == 0); kill(getpid(), SIGSTOP); getppid(); return 0; } assert(pid == wait(&status)); assert(ptrace(PTRACE_SETOPTIONS, pid, 0, PTRACE_O_TRACESYSGOOD) == 0); assert(ptrace(PTRACE_SYSCALL, pid, 0,0) == 0); assert(pid == wait(&status)); assert(ptrace(PTRACE_SINGLESTEP, pid, 0,0) == 0); assert(pid == wait(&status)); if (status == 0x57F) return 0; printf("kernel bug: status=%X shouldn't have 0x80\n", status); return 1; } Signed-off-by: -
Oleg Nesterov authored
Suggested by Roland. Implement user_single_step_siginfo() for powerpc. Signed-off-by:
-
Oleg Nesterov authored
Suggested by Roland. Currently there is no way to synthesize a single-stepping trap in the arch-independent manner. This patch adds the default helper which fills siginfo_t, arch/ can can override it. Architetures which implement user_enable_single_step() should add user_single_step_siginfo() also. Signed-off-by:
-
Oleg Nesterov authored
If the tracee calls fork() after PTRACE_SINGLESTEP, the forked child starts with TIF_SINGLESTEP/X86_EFLAGS_TF bits copied from ptraced parent. This is not right, especially when the new child is not auto-attaced: in this case it is killed by SIGTRAP. Change copy_process() to call user_disable_single_step(). Tested on x86. Test-case: #include <stdio.h> #include <unistd.h> #include <signal.h> #include <sys/ptrace.h> #include <sys/wait.h> #include <assert.h> int main(void) { int pid, status; if (!(pid = fork())) { assert(ptrace(PTRACE_TRACEME) == 0); kill(getpid(), SIGSTOP); if (!fork()) { /* kernel bug: this child will be killed by SIGTRAP */ printf("Hello world\n"); return 43; } wait(&status); return WEXITSTATUS(status); } for (;;) { assert(pid == wait(&status)); if (WIFEXITED(status)) break; assert(ptrace(PTRACE_SINGLESTEP, pid, 0,0) == 0); } assert(WEXITSTATUS(status) == 43); return 0; } Signed-off-by: -
Oleg Nesterov authored
No functional changes. ptrace_init_task() looks confusing, as if we always auto-attach when "bool ptrace" argument is true, while in fact we attach only if current is traced. Make the code more explicit and kill now unused ptrace_link(). Signed-off-by:
-
Bob Liu authored
Variable `progress' isn't used in mem_cgroup_resize_limit() any more. Remove it. [akpm@linux-foundation.org: cleanup] Signed-off-by:
Bob Liu <lliubbo@gmail.com> Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Reviewed-by:
Balbir Singh <balbir@linux.vnet.ibm.com> Signed-off-by:
-
Daisuke Nishimura authored
memcg_tasklist was introduced at commit 7f4d454d(memcg: avoid deadlock caused by race between oom and cpuset_attach) instead of cgroup_mutex to fix a deadlock problem. The cgroup_mutex, which was removed by the commit, in mem_cgroup_out_of_memory() was originally introduced at commit c7ba5c9e (Memory controller: OOM handling). IIUC, the intention of this cgroup_mutex was to prevent task move during select_bad_process() so that situations like below can be avoided. Assume cgroup "foo" has exceeded its limit and is about to trigger oom. 1. Process A, which has been in cgroup "baa" and uses large memory, is just moved to cgroup "foo". Process A can be the candidates for being killed. 2. Process B, which has been in cgroup "foo" and uses large memory, is just moved from cgroup "foo". Process B can be excluded from the candidates for being killed. But these race window exists anyway even if we hold a lock, because __mem_cgroup_try_charge() decides wether it should trigger oom or not outside of the lock. So the original cgroup_mutex in mem_cgroup_out_of_memory and thus current memcg_tasklist has no use. And IMHO, those races are not so critical for users. This patch removes it and make codes simpler. Signed-off-by:
Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Cc: Balbir Singh <balbir@linux.vnet.ibm.com> Acked-by:
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by:
-
Daisuke Nishimura authored
task_in_mem_cgroup(), which is called by select_bad_process() to check whether a task can be a candidate for being oom-killed from memcg's limit, checks "curr->use_hierarchy"("curr" is the mem_cgroup the task belongs to). But this check return true(it's false positive) when: <some path>/aa use_hierarchy == 0 <- hitting limit <some path>/aa/00 use_hierarchy == 1 <- the task belongs to This leads to killing an innocent task in aa/00. This patch is a fix for this bug. And this patch also fixes the arg for mem_cgroup_print_oom_info(). We should print information of mem_cgroup which the task being killed, not current, belongs to. Signed-off-by: -
Daisuke Nishimura authored
mem_cgroup_move_parent() calls try_charge first and cancel_charge on failure. IMHO, charge/uncharge(especially charge) is high cost operation, so we should avoid it as far as possible. This patch tries to delay try_charge in mem_cgroup_move_parent() by re-ordering checks it does. And this patch renames mem_cgroup_move_account() to __mem_cgroup_move_account(), changes the return value of __mem_cgroup_move_account() from int to void, and adds a new wrapper(mem_cgroup_move_account()), which checks whether a @pc is valid for moving account and calls __mem_cgroup_move_account(). This patch removes the last caller of trylock_page_cgroup(), so removes its definition too. Signed-off-by:
-
Daisuke Nishimura authored
There are some places calling both res_counter_uncharge() and css_put() to cancel the charge and the refcnt we have got by mem_cgroup_tyr_charge(). This patch introduces mem_cgroup_cancel_charge() and call it in those places. Signed-off-by:
-
KAMEZAWA Hiroyuki authored
In global VM, FILE_MAPPED is used but memcg uses MAPPED_FILE. This makes grep difficult. Replace memcg's MAPPED_FILE with FILE_MAPPED And in global VM, mapped shared memory is accounted into FILE_MAPPED. But memcg doesn't. fix it. Note: page_is_file_cache() just checks SwapBacked or not. So, we need to check PageAnon. Cc: Balbir Singh <balbir@in.ibm.com> Reviewed-by:
-
KAMEZAWA Hiroyuki authored
This is a patch for coalescing access to res_counter at charging by percpu caching. At charge, memcg charges 64pages and remember it in percpu cache. Because it's cache, drain/flush if necessary. This version uses public percpu area. 2 benefits for using public percpu area. 1. Sum of stocked charge in the system is limited to # of cpus not to the number of memcg. This shows better synchonization. 2. drain code for flush/cpuhotplug is very easy (and quick) The most important point of this patch is that we never touch res_counter in fast path. The res_counter is system-wide shared counter which is modified very frequently. We shouldn't touch it as far as we can for avoiding false sharing. On x86-64 8cpu server, I tested overheads of memcg at page fault by running a program which does map/fault/unmap in a loop. Running a task per a cpu by taskset and see sum of the number of page faults in 60secs. [without memcg config] 40156968 page-faults # 0.085 M/sec ( +- 0.046% ) 27.67 cache-miss/faults [root cgroup] 36659599 page-faults # 0.077 M/sec ( +- 0.247% ) 31.58 cache miss/faults [in a child cgroup] 18444157 page-faults # 0.039 M/sec ( +- 0.133% ) 69.96 cache miss/faults [ + coalescing uncharge patch] 27133719 page-faults # 0.057 M/sec ( +- 0.155% ) 47.16 cache miss/faults [ + coalescing uncharge patch + this patch ] 34224709 page-faults # 0.072 M/sec ( +- 0.173% ) 34.69 cache miss/faults Changelog (since Oct/2): - updated comments - replaced get_cpu_var() with __get_cpu_var() if possible. - removed mutex for system-wide drain. adds a counter instead of it. - removed CONFIG_HOTPLUG_CPU Changelog (old): - rebased onto the latest mmotm - moved charge size check before __GFP_WAIT check for avoiding unnecesary - added asynchronous flush routine. - fixed bugs pointed out by Nishimura-san. [akpm@linux-foundation.org: tweak comments] [nishimura@mxp.nes.nec.co.jp: don't do INIT_WORK() repeatedly against the same work_struct] Signed-off-by: -
KAMEZAWA Hiroyuki authored
In massive parallel enviroment, res_counter can be a performance bottleneck. One strong techinque to reduce lock contention is reducing calls by coalescing some amount of calls into one. Considering charge/uncharge chatacteristic, - charge is done one by one via demand-paging. - uncharge is done by - in chunk at munmap, truncate, exit, execve... - one by one via vmscan/paging. It seems we have a chance to coalesce uncharges for improving scalability at unmap/truncation. This patch is a for coalescing uncharge. For avoiding scattering memcg's structure to functions under /mm, this patch adds memcg batch uncharge information to the task. A reason for per-task batching is for making use of caller's context information. We do batched uncharge (deleyed uncharge) when truncation/unmap occurs but do direct uncharge when uncharge is called by memory reclaim (vmscan.c). The degree of coalescing depends on callers - at invalidate/trucate... pagevec size - at unmap ....ZAP_BLOCK_SIZE (memory itself will be freed in this degree.) Then, we'll not coalescing too much. On x86-64 8cpu server, I tested overheads of memcg at page fault by running a program which does map/fault/unmap in a loop. Running a task per a cpu by taskset and see sum of the number of page faults in 60secs. [without memcg config] 40156968 page-faults # 0.085 M/sec ( +- 0.046% ) 27.67 cache-miss/faults [root cgroup] 36659599 page-faults # 0.077 M/sec ( +- 0.247% ) 31.58 miss/faults [in a child cgroup] 18444157 page-faults # 0.039 M/sec ( +- 0.133% ) 69.96 miss/faults [child with this patch] 27133719 page-faults # 0.057 M/sec ( +- 0.155% ) 47.16 miss/faults We can see some amounts of improvement. (root cgroup doesn't affected by this patch) Another patch for "charge" will follow this and above will be improved more. Changelog(since 2009/10/02): - renamed filed of memcg_batch (as pages to bytes, memsw to memsw_bytes) - some clean up and commentary/description updates. - added initialize code to copy_process(). (possible bug fix) Changelog(old): - fixed !CONFIG_MEM_CGROUP case. - rebased onto the latest mmotm + softlimit fix patches. - unified patch for callers - added commetns. - make ->do_batch as bool. - removed css_get() at el. We don't need it. Signed-off-by:
-
Kirill A. Shutemov authored
A memory cgroup has a memory.memsw.usage_in_bytes file. It shows the sum of the usage of pages and swapents in the cgroup. Presently the root cgroup's memsw.usage_in_bytes shows the wrong value - the number of swapents are not added. So take MEM_CGROUP_STAT_SWAPOUT into account. Signed-off-by:
Kirill A. Shutemov <kirill@shutemov.name> Reviewed-by:
-
Alexey Dobriyan authored
Using create_proc_entry() + ->proc_fops assignment is racy because ->proc_fops will be NULL for some time, use proc_create() to avoid race. Signed-off-by:
Alexey Dobriyan <adobriyan@gmail.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Cc: Jonathan Corbet <corbet@lwn.net> Signed-off-by:
-
Alexey Dobriyan authored
Example is outdated, it still uses old ->read_proc interfaces and "fb" example is plain racy. There are better examples all over the tree. Docbook itself says almost nothing about /proc and contain quite a number of simply wrong facts, e.g. device nodes support. What it does is describing at great length interface which are going to be removed. There are Documentation/filesystems/seq_file.txt in exchange. Signed-off-by:
Erik Mouw <mouw@nl.linux.org> Cc: Randy Dunlap <randy.dunlap@oracle.com> Signed-off-by:
-
Randy Dunlap authored
If a patch adds ioctls, then Documentation/ioctl/ioctl-number.txt should also be updated. Remove reference to the OSDL PLM build farm. Signed-off-by:
Randy Dunlap <randy.dunlap@oracle.com> Signed-off-by:
-
Zhaolei authored
It is not necessary to write custom code for convert calendar time to broken-down time. time_to_tm() is more generic to do that. Signed-off-by:
Zhao Lei <zhaolei@cn.fujitsu.com> Cc: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@elte.hu> Cc: Pavel Machek <pavel@ucw.cz> Cc: Andi Kleen <andi@firstfloor.org> Signed-off-by:
-
Akinobu Mita authored
Use bitmap_weight instead of doing hweight32 for each 32bit in bitmap. Signed-off-by:
Akinobu Mita <akinobu.mita@gmail.com> Cc: Mikulas Patocka <mikulas@artax.karlin.mff.cuni.cz> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by:
-
Akinobu Mita authored
Use hweight32 instead of counting for each bit Signed-off-by:
-
Alexey Dobriyan authored
* small define cleanup in header * fix #ifdeffery in procfs.c via Kconfig Signed-off-by:
-
Alexey Dobriyan authored
/proc/fs/reiserfs/version is on the way of removing ->read_proc interface. It's empty however, so simply remove it instead of doing dummy conversion. It's hard to see what information userspace can extract from empty file. Signed-off-by:
-
Alexey Dobriyan authored
Signed-off-by:
Evgeniy Dushistov <dushistov@mail.ru> Cc: Christoph Hellwig <hch@lst.de> Signed-off-by:
-
Alexey Dobriyan authored
Signed-off-by:
-
Jan Kara authored
When an IO error happens while writing metadata buffers, we should better report it and call ext2_error since the filesystem is probably no longer consistent. Sometimes such IO errors happen while flushing thread does background writeback, the buffer gets later evicted from memory, and thus the only trace of the error remains as AS_EIO bit set in blockdevice's mapping. So we check this bit in ext2_fsync and report the error although we cannot be really sure which buffer we failed to write. Signed-off-by:
Jan Kara <jack@suse.cz> Cc: Chris Mason <chris.mason@oracle.com> Signed-off-by:
-
