Manfred Spraul b869d5be0a ipc/util.c: use binary search for max_idx ... If semctl(), msgctl() and shmctl() are called with IPC_INFO, SEM_INFO, MSG_INFO or SHM_INFO, then the return value is the index of the highest used index in the kernel's internal array recording information about all SysV objects of the requested type for the current namespace. (This information can be used with repeated ..._STAT or ..._STAT_ANY operations to obtain information about all SysV objects on the system.) There is a cache for this value. But when the cache needs up be updated, then the highest used index is determined by looping over all possible values. With the introduction of IPCMNI_EXTEND_SHIFT, this could be a loop over 16 million entries. And due to /proc/sys/kernel/*next_id, the index values do not need to be consecutive. With <write 16000000 to msg_next_id>, msgget(), msgctl(,IPC_RMID) in a loop, I have observed a performance increase of around factor 13000. As there is no get_last() function for idr structures: Implement a "get_last()" using a binary search. As far as I see, ipc is the only user that needs get_last(), thus implement it in ipc/util.c and not in a central location. [akpm@linux-foundation.org: tweak comment, fix typo] Link: https://lkml.kernel.org/r/20210425075208.11777-2-manfred@colorfullife.com Signed-off-by: Manfred Spraul <manfred@colorfullife.com> Acked-by: Davidlohr Bueso <dbueso@suse.de> Cc: <1vier1@web.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>		2021-07-01 11:06:07 -07:00
..
compat.c	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
ipc_sysctl.c	ipc: adjust proc_ipc_sem_dointvec definition to match prototype	2020-09-05 12:14:29 -07:00
Makefile	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
mq_sysctl.c	sysctl: pass kernel pointers to ->proc_handler	2020-04-27 02:07:40 -04:00
mqueue.c	ipc/mqueue, msg, sem: avoid relying on a stack reference past its expiry	2021-05-22 15:09:07 -10:00
msg.c	ipc: use kmalloc for msg_queue and shmid_kernel	2021-07-01 11:06:07 -07:00
msgutil.c	ipc: Use generic ns_common::count	2020-08-19 14:13:52 +02:00
namespace.c	ipc: Use generic ns_common::count	2020-08-19 14:13:52 +02:00
sem.c	ipc/sem.c: use READ_ONCE()/WRITE_ONCE() for use_global_lock	2021-07-01 11:06:07 -07:00
shm.c	ipc: use kmalloc for msg_queue and shmid_kernel	2021-07-01 11:06:07 -07:00
syscall.c	y2038: remove CONFIG_64BIT_TIME	2019-11-15 14:38:27 +01:00
util.c	ipc/util.c: use binary search for max_idx	2021-07-01 11:06:07 -07:00
util.h	ipc/util.c: use binary search for max_idx	2021-07-01 11:06:07 -07:00