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

Kefeng Wang
2022-08-17T07:17:06Z

On 2022/8/16 16:44, 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.
Add more experts according to commit d8a759b57035，
any advice would be much appreciated，thanks.
> 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"
> "Node %d MemUsed: %8lu kB\n"
> "Node %d SwapCached: %8lu kB\n"
> "Node %d Active: %8lu kB\n"
> @@ -397,7 +408,8 @@ static ssize_t node_read_meminfo(struct device *dev,
> "Node %d Mlocked: %8lu kB\n",
> nid, K(i.totalram),
> nid, K(i.freeram),
> - nid, K(i.totalram - i.freeram),
> + nid, K(free_pcp),
> + nid, K(i.totalram - i.freeram - free_pcp),
> nid, K(swapcached),
> nid, K(node_page_state(pgdat, NR_ACTIVE_ANON) +
> node_page_state(pgdat, NR_ACTIVE_FILE)),
> diff --git a/fs/proc/meminfo.c b/fs/proc/meminfo.c
> index 6e89f0e2fd20..672c784dfc8a 100644
> --- a/fs/proc/meminfo.c
> +++ b/fs/proc/meminfo.c
> @@ -38,6 +38,9 @@ static int meminfo_proc_show(struct seq_file *m, void *v)
> unsigned long pages[NR_LRU_LISTS];
> unsigned long sreclaimable, sunreclaim;
> int lru;
> + unsigned long free_pcp = 0;
> + struct zone *zone;
> + int cpu;
>
> si_meminfo(&i);
> si_swapinfo(&i);
> @@ -55,8 +58,14 @@ static int meminfo_proc_show(struct seq_file *m, void *v)
> sreclaimable = global_node_page_state_pages(NR_SLAB_RECLAIMABLE_B);
> sunreclaim = global_node_page_state_pages(NR_SLAB_UNRECLAIMABLE_B);
>
> + for_each_populated_zone(zone) {
> + for_each_online_cpu(cpu)
> + free_pcp += per_cpu_ptr(zone->per_cpu_pageset, cpu)->count;
> + }
> +
> show_val_kb(m, "MemTotal: ", i.totalram);
> show_val_kb(m, "MemFree: ", i.freeram);
> + show_val_kb(m, "PcpFree: ", free_pcp);
> show_val_kb(m, "MemAvailable: ", available);
> show_val_kb(m, "Buffers: ", i.bufferram);
> show_val_kb(m, "Cached: ", cached);