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    SubjectRe: [PATCH RFC] mm, proc: add PcpFree to meminfo
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    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?

    >
    > Can you send a patch to do that instead please?
    >
    > thanks,
    >
    > greg k-h
    > .

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