* [PATCH net-next v3 1/2] net: netpoll: Individualize the skb pool
2024-11-14 11:00 [PATCH net-next v3 0/2] net: netpoll: Improve SKB pool management Breno Leitao
@ 2024-11-14 11:00 ` Breno Leitao
2024-11-14 11:00 ` [PATCH net-next v3 2/2] net: netpoll: flush skb pool during cleanup Breno Leitao
2024-11-16 2:00 ` [PATCH net-next v3 0/2] net: netpoll: Improve SKB pool management patchwork-bot+netdevbpf
2 siblings, 0 replies; 4+ messages in thread
From: Breno Leitao @ 2024-11-14 11:00 UTC (permalink / raw)
To: David S. Miller, Eric Dumazet, Jakub Kicinski, Paolo Abeni, Simon Horman
Cc: netdev, linux-kernel, Breno Leitao, max, davej, vlad.wing
The current implementation of the netpoll system uses a global skb
pool, which can lead to inefficient memory usage and
waste when targets are disabled or no longer in use.
This can result in a significant amount of memory being unnecessarily
allocated and retained, potentially causing performance issues and
limiting the availability of resources for other system components.
Modify the netpoll system to assign a skb pool to each target instead of
using a global one.
This approach allows for more fine-grained control over memory
allocation and deallocation, ensuring that resources are only allocated
and retained as needed.
Signed-off-by: Breno Leitao <leitao@debian.org>
---
include/linux/netpoll.h | 1 +
net/core/netpoll.c | 31 +++++++++++++------------------
2 files changed, 14 insertions(+), 18 deletions(-)
diff --git a/include/linux/netpoll.h b/include/linux/netpoll.h
index cd4e28db0cbd77572a579aff2067b5864d1a904a..77635b885c18b7d405642c2e7f39f5ff2c7d469d 100644
--- a/include/linux/netpoll.h
+++ b/include/linux/netpoll.h
@@ -32,6 +32,7 @@ struct netpoll {
bool ipv6;
u16 local_port, remote_port;
u8 remote_mac[ETH_ALEN];
+ struct sk_buff_head skb_pool;
};
struct netpoll_info {
diff --git a/net/core/netpoll.c b/net/core/netpoll.c
index 94b7f07a952fff3358cc609fb29de33ae8ae8626..719c9aae845fbeb6f5b53a2bef675d3cb8cd44a7 100644
--- a/net/core/netpoll.c
+++ b/net/core/netpoll.c
@@ -45,9 +45,6 @@
#define MAX_UDP_CHUNK 1460
#define MAX_SKBS 32
-
-static struct sk_buff_head skb_pool;
-
#define USEC_PER_POLL 50
#define MAX_SKB_SIZE \
@@ -234,20 +231,23 @@ void netpoll_poll_enable(struct net_device *dev)
up(&ni->dev_lock);
}
-static void refill_skbs(void)
+static void refill_skbs(struct netpoll *np)
{
+ struct sk_buff_head *skb_pool;
struct sk_buff *skb;
unsigned long flags;
- spin_lock_irqsave(&skb_pool.lock, flags);
- while (skb_pool.qlen < MAX_SKBS) {
+ skb_pool = &np->skb_pool;
+
+ spin_lock_irqsave(&skb_pool->lock, flags);
+ while (skb_pool->qlen < MAX_SKBS) {
skb = alloc_skb(MAX_SKB_SIZE, GFP_ATOMIC);
if (!skb)
break;
- __skb_queue_tail(&skb_pool, skb);
+ __skb_queue_tail(skb_pool, skb);
}
- spin_unlock_irqrestore(&skb_pool.lock, flags);
+ spin_unlock_irqrestore(&skb_pool->lock, flags);
}
static void zap_completion_queue(void)
@@ -284,12 +284,12 @@ static struct sk_buff *find_skb(struct netpoll *np, int len, int reserve)
struct sk_buff *skb;
zap_completion_queue();
- refill_skbs();
+ refill_skbs(np);
repeat:
skb = alloc_skb(len, GFP_ATOMIC);
if (!skb)
- skb = skb_dequeue(&skb_pool);
+ skb = skb_dequeue(&np->skb_pool);
if (!skb) {
if (++count < 10) {
@@ -673,6 +673,8 @@ int netpoll_setup(struct netpoll *np)
struct in_device *in_dev;
int err;
+ skb_queue_head_init(&np->skb_pool);
+
rtnl_lock();
if (np->dev_name[0]) {
struct net *net = current->nsproxy->net_ns;
@@ -773,7 +775,7 @@ int netpoll_setup(struct netpoll *np)
}
/* fill up the skb queue */
- refill_skbs();
+ refill_skbs(np);
err = __netpoll_setup(np, ndev);
if (err)
@@ -792,13 +794,6 @@ int netpoll_setup(struct netpoll *np)
}
EXPORT_SYMBOL(netpoll_setup);
-static int __init netpoll_init(void)
-{
- skb_queue_head_init(&skb_pool);
- return 0;
-}
-core_initcall(netpoll_init);
-
static void rcu_cleanup_netpoll_info(struct rcu_head *rcu_head)
{
struct netpoll_info *npinfo =
--
2.43.5
^ permalink raw reply [flat|nested] 4+ messages in thread* [PATCH net-next v3 2/2] net: netpoll: flush skb pool during cleanup
2024-11-14 11:00 [PATCH net-next v3 0/2] net: netpoll: Improve SKB pool management Breno Leitao
2024-11-14 11:00 ` [PATCH net-next v3 1/2] net: netpoll: Individualize the skb pool Breno Leitao
@ 2024-11-14 11:00 ` Breno Leitao
2024-11-16 2:00 ` [PATCH net-next v3 0/2] net: netpoll: Improve SKB pool management patchwork-bot+netdevbpf
2 siblings, 0 replies; 4+ messages in thread
From: Breno Leitao @ 2024-11-14 11:00 UTC (permalink / raw)
To: David S. Miller, Eric Dumazet, Jakub Kicinski, Paolo Abeni, Simon Horman
Cc: netdev, linux-kernel, Breno Leitao, max, davej, vlad.wing
The netpoll subsystem maintains a pool of 32 pre-allocated SKBs per
instance, but these SKBs are not freed when the netpoll user is brought
down. This leads to memory waste as these buffers remain allocated but
unused.
Add skb_pool_flush() to properly clean up these SKBs when netconsole is
terminated, improving memory efficiency.
Signed-off-by: Breno Leitao <leitao@debian.org>
---
net/core/netpoll.c | 14 +++++++++++++-
1 file changed, 13 insertions(+), 1 deletion(-)
diff --git a/net/core/netpoll.c b/net/core/netpoll.c
index 719c9aae845fbeb6f5b53a2bef675d3cb8cd44a7..00e1e4a329022ddcef32d72f1828acaf58cc94fa 100644
--- a/net/core/netpoll.c
+++ b/net/core/netpoll.c
@@ -531,6 +531,14 @@ static int netpoll_parse_ip_addr(const char *str, union inet_addr *addr)
return -1;
}
+static void skb_pool_flush(struct netpoll *np)
+{
+ struct sk_buff_head *skb_pool;
+
+ skb_pool = &np->skb_pool;
+ skb_queue_purge_reason(skb_pool, SKB_CONSUMED);
+}
+
int netpoll_parse_options(struct netpoll *np, char *opt)
{
char *cur=opt, *delim;
@@ -779,10 +787,12 @@ int netpoll_setup(struct netpoll *np)
err = __netpoll_setup(np, ndev);
if (err)
- goto put;
+ goto flush;
rtnl_unlock();
return 0;
+flush:
+ skb_pool_flush(np);
put:
DEBUG_NET_WARN_ON_ONCE(np->dev);
if (ip_overwritten)
@@ -830,6 +840,8 @@ void __netpoll_cleanup(struct netpoll *np)
call_rcu(&npinfo->rcu, rcu_cleanup_netpoll_info);
} else
RCU_INIT_POINTER(np->dev->npinfo, NULL);
+
+ skb_pool_flush(np);
}
EXPORT_SYMBOL_GPL(__netpoll_cleanup);
--
2.43.5
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH net-next v3 0/2] net: netpoll: Improve SKB pool management
2024-11-14 11:00 [PATCH net-next v3 0/2] net: netpoll: Improve SKB pool management Breno Leitao
2024-11-14 11:00 ` [PATCH net-next v3 1/2] net: netpoll: Individualize the skb pool Breno Leitao
2024-11-14 11:00 ` [PATCH net-next v3 2/2] net: netpoll: flush skb pool during cleanup Breno Leitao
@ 2024-11-16 2:00 ` patchwork-bot+netdevbpf
2 siblings, 0 replies; 4+ messages in thread
From: patchwork-bot+netdevbpf @ 2024-11-16 2:00 UTC (permalink / raw)
To: Breno Leitao
Cc: davem, edumazet, kuba, pabeni, horms, netdev, linux-kernel, max,
davej, vlad.wing
Hello:
This series was applied to netdev/net-next.git (main)
by Jakub Kicinski <kuba@kernel.org>:
On Thu, 14 Nov 2024 03:00:10 -0800 you wrote:
> The netpoll subsystem pre-allocates 32 SKBs in a pool for emergency use
> during out-of-memory conditions. However, the current implementation has
> several inefficiencies:
>
> * The SKB pool, once allocated, is never freed:
> * Resources remain allocated even after netpoll users are removed
> * Failed initialization can leave pool populated forever
> * The global pool design makes resource tracking difficult
>
> [...]
Here is the summary with links:
- [net-next,v3,1/2] net: netpoll: Individualize the skb pool
https://git.kernel.org/netdev/net-next/c/221a9c1df790
- [net-next,v3,2/2] net: netpoll: flush skb pool during cleanup
https://git.kernel.org/netdev/net-next/c/6c59f16f1770
You are awesome, thank you!
--
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html
^ permalink raw reply [flat|nested] 4+ messages in thread