Messages in this thread | | | Date | Sun, 11 Mar 2007 12:01:42 +0300 | From | Pavel Emelianov <> | Subject | Re: [RFC][PATCH 1/7] Resource counters |
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Herbert Poetzl wrote: > On Wed, Mar 07, 2007 at 10:19:05AM +0300, Pavel Emelianov wrote: >> Balbir Singh wrote: >>> Pavel Emelianov wrote: >>>> Introduce generic structures and routines for >>>> resource accounting. >>>> >>>> Each resource accounting container is supposed to >>>> aggregate it, container_subsystem_state and its >>>> resource-specific members within. >>>> >>>> >>>> ------------------------------------------------------------------------ >>>> >>>> diff -upr linux-2.6.20.orig/include/linux/res_counter.h >>>> linux-2.6.20-0/include/linux/res_counter.h >>>> --- linux-2.6.20.orig/include/linux/res_counter.h 2007-03-06 >>>> 13:39:17.000000000 +0300 >>>> +++ linux-2.6.20-0/include/linux/res_counter.h 2007-03-06 >>>> 13:33:28.000000000 +0300 >>>> @@ -0,0 +1,83 @@ >>>> +#ifndef __RES_COUNTER_H__ >>>> +#define __RES_COUNTER_H__ >>>> +/* >>>> + * resource counters >>>> + * >>>> + * Copyright 2007 OpenVZ SWsoft Inc >>>> + * >>>> + * Author: Pavel Emelianov <xemul@openvz.org> >>>> + * >>>> + */ >>>> + >>>> +#include <linux/container.h> >>>> + >>>> +struct res_counter { >>>> + unsigned long usage; >>>> + unsigned long limit; >>>> + unsigned long failcnt; >>>> + spinlock_t lock; >>>> +}; >>>> + >>>> +enum { >>>> + RES_USAGE, >>>> + RES_LIMIT, >>>> + RES_FAILCNT, >>>> +}; >>>> + >>>> +ssize_t res_counter_read(struct res_counter *cnt, int member, >>>> + const char __user *buf, size_t nbytes, loff_t *pos); >>>> +ssize_t res_counter_write(struct res_counter *cnt, int member, >>>> + const char __user *buf, size_t nbytes, loff_t *pos); >>>> + >>>> +static inline void res_counter_init(struct res_counter *cnt) >>>> +{ >>>> + spin_lock_init(&cnt->lock); >>>> + cnt->limit = (unsigned long)LONG_MAX; >>>> +} >>>> + >>> Is there any way to indicate that there are no limits on this container. >> Yes - LONG_MAX is essentially a "no limit" value as no >> container will ever have such many files :) > > -1 or ~0 is a viable choice for userspace to > communicate 'infinite' or 'unlimited'
OK, I'll make ULONG_MAX :)
>>> LONG_MAX is quite huge, but still when the administrator wants to >>> configure a container to *un-limited usage*, it becomes hard for >>> the administrator. >>> >>>> +static inline int res_counter_charge_locked(struct res_counter *cnt, >>>> + unsigned long val) >>>> +{ >>>> + if (cnt->usage <= cnt->limit - val) { >>>> + cnt->usage += val; >>>> + return 0; >>>> + } >>>> + >>>> + cnt->failcnt++; >>>> + return -ENOMEM; >>>> +} >>>> + >>>> +static inline int res_counter_charge(struct res_counter *cnt, >>>> + unsigned long val) >>>> +{ >>>> + int ret; >>>> + unsigned long flags; >>>> + >>>> + spin_lock_irqsave(&cnt->lock, flags); >>>> + ret = res_counter_charge_locked(cnt, val); >>>> + spin_unlock_irqrestore(&cnt->lock, flags); >>>> + return ret; >>>> +} >>>> + >>> Will atomic counters help here. >> I'm afraid no. We have to atomically check for limit and alter >> one of usage or failcnt depending on the checking result. Making >> this with atomic_xxx ops will require at least two ops. > > Linux-VServer does the accounting with atomic counters, > so that works quite fine, just do the checks at the > beginning of whatever resource allocation and the > accounting once the resource is acquired ...
This works quite fine on non-preempted kernels. From the time you checked for resource till you really account it kernel may preempt and let another process pass through vx_anything_avail() check.
>> If we'll remove failcnt this would look like >> while (atomic_cmpxchg(...)) >> which is also not that good. >> >> Moreover - in RSS accounting patches I perform page list >> manipulations under this lock, so this also saves one atomic op. > > it still hasn't been shown that this kind of RSS limit > doesn't add big time overhead to normal operations > (inside and outside of such a resource container) > > note that the 'usual' memory accounting is much more > lightweight and serves similar purposes ...
It OOM-kills current int case of limit hit instead of reclaiming pages or killing *memory eater* to free memory.
> best, > Herbert > >>>> +static inline void res_counter_uncharge_locked(struct res_counter *cnt, >>>> + unsigned long val) >>>> +{ >>>> + if (unlikely(cnt->usage < val)) { >>>> + WARN_ON(1); >>>> + val = cnt->usage; >>>> + } >>>> + >>>> + cnt->usage -= val; >>>> +} >>>> + >>>> +static inline void res_counter_uncharge(struct res_counter *cnt, >>>> + unsigned long val) >>>> +{ >>>> + unsigned long flags; >>>> + >>>> + spin_lock_irqsave(&cnt->lock, flags); >>>> + res_counter_uncharge_locked(cnt, val); >>>> + spin_unlock_irqrestore(&cnt->lock, flags); >>>> +} >>>> + >>>> +#endif >>>> diff -upr linux-2.6.20.orig/init/Kconfig linux-2.6.20-0/init/Kconfig >>>> --- linux-2.6.20.orig/init/Kconfig 2007-03-06 13:33:28.000000000 +0300 >>>> +++ linux-2.6.20-0/init/Kconfig 2007-03-06 13:33:28.000000000 +0300 >>>> @@ -265,6 +265,10 @@ config CPUSETS >>>> >>>> Say N if unsure. >>>> >>>> +config RESOURCE_COUNTERS >>>> + bool >>>> + select CONTAINERS >>>> + >>>> config SYSFS_DEPRECATED >>>> bool "Create deprecated sysfs files" >>>> default y >>>> diff -upr linux-2.6.20.orig/kernel/Makefile >>>> linux-2.6.20-0/kernel/Makefile >>>> --- linux-2.6.20.orig/kernel/Makefile 2007-03-06 13:33:28.000000000 >>>> +0300 >>>> +++ linux-2.6.20-0/kernel/Makefile 2007-03-06 13:33:28.000000000 +0300 >>>> @@ -51,6 +51,7 @@ obj-$(CONFIG_RELAY) += relay.o >>>> obj-$(CONFIG_UTS_NS) += utsname.o >>>> obj-$(CONFIG_TASK_DELAY_ACCT) += delayacct.o >>>> obj-$(CONFIG_TASKSTATS) += taskstats.o tsacct.o >>>> +obj-$(CONFIG_RESOURCE_COUNTERS) += res_counter.o >>>> >>>> ifneq ($(CONFIG_SCHED_NO_NO_OMIT_FRAME_POINTER),y) >>>> # According to Alan Modra <alan@linuxcare.com.au>, the >>>> -fno-omit-frame-pointer is >>>> diff -upr linux-2.6.20.orig/kernel/res_counter.c >>>> linux-2.6.20-0/kernel/res_counter.c >>>> --- linux-2.6.20.orig/kernel/res_counter.c 2007-03-06 >>>> 13:39:17.000000000 +0300 >>>> +++ linux-2.6.20-0/kernel/res_counter.c 2007-03-06 >>>> 13:33:28.000000000 +0300 >>>> @@ -0,0 +1,72 @@ >>>> +/* >>>> + * resource containers >>>> + * >>>> + * Copyright 2007 OpenVZ SWsoft Inc >>>> + * >>>> + * Author: Pavel Emelianov <xemul@openvz.org> >>>> + * >>>> + */ >>>> + >>>> +#include <linux/parser.h> >>>> +#include <linux/fs.h> >>>> +#include <linux/res_counter.h> >>>> +#include <asm/uaccess.h> >>>> + >>>> +static inline unsigned long *res_counter_member(struct res_counter >>>> *cnt, int member) >>>> +{ >>>> + switch (member) { >>>> + case RES_USAGE: >>>> + return &cnt->usage; >>>> + case RES_LIMIT: >>>> + return &cnt->limit; >>>> + case RES_FAILCNT: >>>> + return &cnt->failcnt; >>>> + }; >>>> + >>>> + BUG(); >>>> + return NULL; >>>> +} >>>> + >>>> +ssize_t res_counter_read(struct res_counter *cnt, int member, >>>> + const char __user *userbuf, size_t nbytes, loff_t *pos) >>>> +{ >>>> + unsigned long *val; >>>> + char buf[64], *s; >>>> + >>>> + s = buf; >>>> + val = res_counter_member(cnt, member); >>>> + s += sprintf(s, "%lu\n", *val); >>>> + return simple_read_from_buffer((void __user *)userbuf, nbytes, >>>> + pos, buf, s - buf); >>>> +} >>>> + >>>> +ssize_t res_counter_write(struct res_counter *cnt, int member, >>>> + const char __user *userbuf, size_t nbytes, loff_t *pos) >>>> +{ >>>> + int ret; >>>> + char *buf, *end; >>>> + unsigned long tmp, *val; >>>> + >>>> + buf = kmalloc(nbytes + 1, GFP_KERNEL); >>>> + ret = -ENOMEM; >>>> + if (buf == NULL) >>>> + goto out; >>>> + >>>> + buf[nbytes] = 0; >>>> + ret = -EFAULT; >>>> + if (copy_from_user(buf, userbuf, nbytes)) >>>> + goto out_free; >>>> + >>>> + ret = -EINVAL; >>>> + tmp = simple_strtoul(buf, &end, 10); >>>> + if (*end != '\0') >>>> + goto out_free; >>>> + >>>> + val = res_counter_member(cnt, member); >>>> + *val = tmp; >>>> + ret = nbytes; >>>> +out_free: >>>> + kfree(buf); >>>> +out: >>>> + return ret; >>>> +} >>>> >>> >>> These bits look a little out of sync, with no users for these routines in >>> this patch. Won't you get a compiler warning, compiling this bit alone? >>> >> Nope - when you have a non-static function without users in a >> file no compiler warning produced. >> _______________________________________________ >> Containers mailing list >> Containers@lists.osdl.org >> https://lists.osdl.org/mailman/listinfo/containers >
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