netdev - Re: [PATCH net-next 1/2] net: Keep sk->sk_forward

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Message-ID: <20230512171702.923725-1-shakeelb@google.com>
Date: Fri, 12 May 2023 17:17:01 +0000
From: Shakeel Butt <shakeelb@...gle.com>
To: Cathy Zhang <cathy.zhang@...el.com>
Cc: Shakeel Butt <shakeelb@...gle.com>, Eric Dumazet <edumazet@...gle.com>, 
	Linux MM <linux-mm@...ck.org>, Cgroups <cgroups@...r.kernel.org>, 
	Paolo Abeni <pabeni@...hat.com>, "davem@...emloft.net" <davem@...emloft.net>, 
	"kuba@...nel.org" <kuba@...nel.org>, "Brandeburg@...gle.com" <Brandeburg@...gle.com>, 
	Jesse Brandeburg <jesse.brandeburg@...el.com>, Suresh Srinivas <suresh.srinivas@...el.com>, 
	Tim C Chen <tim.c.chen@...el.com>, Lizhen You <lizhen.you@...el.com>, 
	"eric.dumazet@...il.com" <eric.dumazet@...il.com>, "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: [PATCH net-next 1/2] net: Keep sk->sk_forward_alloc as a proper size

On Fri, May 12, 2023 at 05:51:40AM +0000, Zhang, Cathy wrote:
> 
> 
[...]
> > 
> > Thanks a lot. This tells us that one or both of following scenarios are
> > happening:
> > 
> > 1. In the softirq recv path, the kernel is processing packets from multiple
> > memcgs.
> > 
> > 2. The process running on the CPU belongs to memcg which is different from
> > the memcgs whose packets are being received on that CPU.
> 
> Thanks for sharing the points, Shakeel! Is there any trace records you want to
> collect?
> 

Can you please try the following patch and see if there is any
improvement?


>From 48eb23c8cbb5d6c6086299c8a5ae4b3485c79a8c Mon Sep 17 00:00:00 2001
From: Shakeel Butt <shakeelb@...gle.com>
Date: Fri, 12 May 2023 17:04:35 +0000
Subject: [PATCH] No batch charge in irq context

---
 mm/memcontrol.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index d31fb1e2cb33..f1453a140fc8 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2652,7 +2652,8 @@ void mem_cgroup_handle_over_high(void)
 static int try_charge_memcg(struct mem_cgroup *memcg, gfp_t gfp_mask,
 			unsigned int nr_pages)
 {
-	unsigned int batch = max(MEMCG_CHARGE_BATCH, nr_pages);
+	unsigned int batch = in_task() ?
+		max(MEMCG_CHARGE_BATCH, nr_pages) : nr_pages;
 	int nr_retries = MAX_RECLAIM_RETRIES;
 	struct mem_cgroup *mem_over_limit;
 	struct page_counter *counter;
-- 
2.40.1.606.ga4b1b128d6-goog