Messages in this thread | | | Date | Tue, 16 Aug 2022 20:03:35 +0800 | Subject | Re: [PATCH RFC] mm, proc: add PcpFree to meminfo | From | Kefeng Wang <> |
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On 2022/8/16 18:50, Greg Kroah-Hartman wrote: > On Tue, Aug 16, 2022 at 06:11:18PM +0800, Kefeng Wang wrote: >> On 2022/8/16 17:16, Greg Kroah-Hartman wrote: >>> On Tue, Aug 16, 2022 at 04:44:26PM +0800, Kefeng Wang wrote: >>>> From: Liu Shixin <liushixin2@huawei.com> >>>> >>>> The page on pcplist could be used, but not counted into memory free or >>>> avaliable, and pcp_free is only showed by show_mem(). Since commit >>>> d8a759b57035 ("mm, page_alloc: double zone's batchsize"), there is a >>>> significant decrease in the display of free memory, with a large number >>>> of cpus and nodes, the number of pages in the percpu list can be very >>>> large, so it is better to let user to know the pcp count. >>>> >>>> Signed-off-by: Liu Shixin <liushixin2@huawei.com> >>>> Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> >>>> --- >>>> drivers/base/node.c | 14 +++++++++++++- >>>> fs/proc/meminfo.c | 9 +++++++++ >>>> 2 files changed, 22 insertions(+), 1 deletion(-) >>>> >>>> diff --git a/drivers/base/node.c b/drivers/base/node.c >>>> index eb0f43784c2b..846864e45db6 100644 >>>> --- a/drivers/base/node.c >>>> +++ b/drivers/base/node.c >>>> @@ -375,6 +375,9 @@ static ssize_t node_read_meminfo(struct device *dev, >>>> struct sysinfo i; >>>> unsigned long sreclaimable, sunreclaimable; >>>> unsigned long swapcached = 0; >>>> + unsigned long free_pcp = 0; >>>> + struct zone *zone; >>>> + int cpu; >>>> si_meminfo_node(&i, nid); >>>> sreclaimable = node_page_state_pages(pgdat, NR_SLAB_RECLAIMABLE_B); >>>> @@ -382,9 +385,17 @@ static ssize_t node_read_meminfo(struct device *dev, >>>> #ifdef CONFIG_SWAP >>>> swapcached = node_page_state_pages(pgdat, NR_SWAPCACHE); >>>> #endif >>>> + for_each_populated_zone(zone) { >>>> + if (zone_to_nid(zone) != nid) >>>> + continue; >>>> + for_each_online_cpu(cpu) >>>> + free_pcp += per_cpu_ptr(zone->per_cpu_pageset, cpu)->count; >>>> + } >>>> + >>>> len = sysfs_emit_at(buf, len, >>>> "Node %d MemTotal: %8lu kB\n" >>>> "Node %d MemFree: %8lu kB\n" >>>> + "Node %d PcpFree: %8lu kB\n" >>> First off, this sysfs file is a huge violation of the normal sysfs >>> rules, so I will not allow any new entries to be added. In fact, the >>> whole thing should just be removed and multiple files created in its >>> place. >> Hi Greg, do you mean to remove all /sys/devices/system/node/node*/meminfo, >> >> but this will beak ABI, is it acceptable? > I do not know, what tool relies on this file? Any userspace tool should > always be able to handle a sysfs file being removed, so you should > probably work with the tool authors to fix this up before removing it.
https://github.com/numactl/numactl/blob/93867c59b0bb29470873a427dc7f06ebaf305221/numastat.c#L841
It seems numastat use this file, but there are maybe more tools,
Cc'ed more mm experts to see more comments.
> > thanks, > > gre gk-h > .
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