Messages in this thread | | | Date | Thu, 27 Mar 2008 13:32:21 +0530 | From | Balbir Singh <> | Subject | Re: [RFC][2/3] Account and control virtual address space allocations (v2) |
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Pavel Emelyanov wrote: > Balbir Singh wrote: >> Changelog v2 >> ------------ >> Change the accounting to what is already present in the kernel. Split >> the address space accounting into mem_cgroup_charge_as and >> mem_cgroup_uncharge_as. At the time of VM expansion, call >> mem_cgroup_cannot_expand_as to check if the new allocation will push >> us over the limit >> >> This patch implements accounting and control of virtual address space. >> Accounting is done when the virtual address space of any task/mm_struct >> belonging to the cgroup is incremented or decremented. This patch >> fails the expansion if the cgroup goes over its limit. >> >> TODOs >> >> 1. Only when CONFIG_MMU is enabled, is the virtual address space control >> enabled. Should we do this for nommu cases as well? My suspicion is >> that we don't have to. >> >> Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com> >> --- >> >> arch/ia64/kernel/perfmon.c | 2 + >> arch/x86/kernel/ptrace.c | 7 +++ >> fs/exec.c | 2 + >> include/linux/memcontrol.h | 26 +++++++++++++ >> include/linux/res_counter.h | 19 ++++++++-- >> init/Kconfig | 2 - >> kernel/fork.c | 17 +++++++-- >> mm/memcontrol.c | 83 ++++++++++++++++++++++++++++++++++++++++++++ >> mm/mmap.c | 11 +++++ >> mm/mremap.c | 2 + >> 10 files changed, 163 insertions(+), 8 deletions(-) >> >> diff -puN mm/memcontrol.c~memory-controller-virtual-address-space-accounting-and-control mm/memcontrol.c >> --- linux-2.6.25-rc5/mm/memcontrol.c~memory-controller-virtual-address-space-accounting-and-control 2008-03-26 16:27:59.000000000 +0530 >> +++ linux-2.6.25-rc5-balbir/mm/memcontrol.c 2008-03-27 00:18:16.000000000 +0530 >> @@ -526,6 +526,76 @@ unsigned long mem_cgroup_isolate_pages(u >> return nr_taken; >> } >> >> +#ifdef CONFIG_CGROUP_MEM_RES_CTLR_AS >> +/* >> + * Charge the address space usage for cgroup. This routine is most >> + * likely to be called from places that expand the total_vm of a mm_struct. >> + */ >> +void mem_cgroup_charge_as(struct mm_struct *mm, long nr_pages) >> +{ >> + struct mem_cgroup *mem; >> + >> + if (mem_cgroup_subsys.disabled) >> + return; >> + >> + rcu_read_lock(); >> + mem = rcu_dereference(mm->mem_cgroup); >> + css_get(&mem->css); >> + rcu_read_unlock(); >> + >> + res_counter_charge(&mem->as_res, (nr_pages * PAGE_SIZE)); >> + css_put(&mem->css); > > Why don't you check whether the counter is charged? This is > bad for two reasons: > 1. you allow for some growth above the limit (e.g. in expand_stack)
I was doing that earlier and then decided to keep the virtual address space code in sync with the RLIMIT_AS checking code in the kernel. If you see the flow, it closely resembles what we do with mm->total_vm and may_expand_vm(). expand_stack() in turn calls acct_stack_growth() which calls may_expand_vm()
> 2. you will undercharge it in the future when uncharging the > vme, whose charge was failed and thus unaccounted.
Hmmm... This should ideally never happen, since we do a may_expand_vm() before expanding the VM and in our case the virtual address space usage. I've not seen it during my runs either. But it is something to keep in mind.
-- Warm Regards, Balbir Singh Linux Technology Center IBM, ISTL
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