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authorGargi Sharma <gs051095@gmail.com>2017-11-17 15:30:30 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2017-11-17 16:10:03 -0800
commit95846ecf9dac5089aed4b144d912225f8ef86ae4 (patch)
tree35da897650335522531d4d4ed37afd2fc26539ec /include/linux
parentf9eb2fdd04d4e68fbea18970bbf65ace716d25b6 (diff)
pid: replace pid bitmap implementation with IDR API
Patch series "Replacing PID bitmap implementation with IDR API", v4. This series replaces kernel bitmap implementation of PID allocation with IDR API. These patches are written to simplify the kernel by replacing custom code with calls to generic code. The following are the stats for pid and pid_namespace object files before and after the replacement. There is a noteworthy change between the IDR and bitmap implementation. Before text data bss dec hex filename 8447 3894 64 12405 3075 kernel/pid.o After text data bss dec hex filename 3397 304 0 3701 e75 kernel/pid.o Before text data bss dec hex filename 5692 1842 192 7726 1e2e kernel/pid_namespace.o After text data bss dec hex filename 2854 216 16 3086 c0e kernel/pid_namespace.o The following are the stats for ps, pstree and calling readdir on /proc for 10,000 processes. ps: With IDR API With bitmap real 0m1.479s 0m2.319s user 0m0.070s 0m0.060s sys 0m0.289s 0m0.516s pstree: With IDR API With bitmap real 0m1.024s 0m1.794s user 0m0.348s 0m0.612s sys 0m0.184s 0m0.264s proc: With IDR API With bitmap real 0m0.059s 0m0.074s user 0m0.000s 0m0.004s sys 0m0.016s 0m0.016s This patch (of 2): Replace the current bitmap implementation for Process ID allocation. Functions that are no longer required, for example, free_pidmap(), alloc_pidmap(), etc. are removed. The rest of the functions are modified to use the IDR API. The change was made to make the PID allocation less complex by replacing custom code with calls to generic API. [gs051095@gmail.com: v6] Link: http://lkml.kernel.org/r/1507760379-21662-2-git-send-email-gs051095@gmail.com [avagin@openvz.org: restore the old behaviour of the ns_last_pid sysctl] Link: http://lkml.kernel.org/r/20171106183144.16368-1-avagin@openvz.org Link: http://lkml.kernel.org/r/1507583624-22146-2-git-send-email-gs051095@gmail.com Signed-off-by: Gargi Sharma <gs051095@gmail.com> Reviewed-by: Rik van Riel <riel@redhat.com> Acked-by: Oleg Nesterov <oleg@redhat.com> Cc: Julia Lawall <julia.lawall@lip6.fr> Cc: Ingo Molnar <mingo@kernel.org> Cc: Pavel Tatashin <pasha.tatashin@oracle.com> Cc: Kirill Tkhai <ktkhai@virtuozzo.com> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Christoph Hellwig <hch@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux')
-rw-r--r--include/linux/pid_namespace.h14
1 files changed, 3 insertions, 11 deletions
diff --git a/include/linux/pid_namespace.h b/include/linux/pid_namespace.h
index c78af6061644..92c6aa509d2e 100644
--- a/include/linux/pid_namespace.h
+++ b/include/linux/pid_namespace.h
@@ -10,15 +10,8 @@
#include <linux/nsproxy.h>
#include <linux/kref.h>
#include <linux/ns_common.h>
+#include <linux/idr.h>
-struct pidmap {
- atomic_t nr_free;
- void *page;
-};
-
-#define BITS_PER_PAGE (PAGE_SIZE * 8)
-#define BITS_PER_PAGE_MASK (BITS_PER_PAGE-1)
-#define PIDMAP_ENTRIES ((PID_MAX_LIMIT+BITS_PER_PAGE-1)/BITS_PER_PAGE)
struct fs_pin;
@@ -30,9 +23,8 @@ enum { /* definitions for pid_namespace's hide_pid field */
struct pid_namespace {
struct kref kref;
- struct pidmap pidmap[PIDMAP_ENTRIES];
+ struct idr idr;
struct rcu_head rcu;
- int last_pid;
unsigned int nr_hashed;
struct task_struct *child_reaper;
struct kmem_cache *pid_cachep;
@@ -106,6 +98,6 @@ static inline int reboot_pid_ns(struct pid_namespace *pid_ns, int cmd)
extern struct pid_namespace *task_active_pid_ns(struct task_struct *tsk);
void pidhash_init(void);
-void pidmap_init(void);
+void pid_idr_init(void);
#endif /* _LINUX_PID_NS_H */