On Fri, 16 Nov 2007 10:35:46 +0100
Eric Dumazet <[EMAIL PROTECTED]> wrote:
> On Fri, 16 Nov 2007 01:12:43 -0800 (PST)
> David Miller <[EMAIL PROTECTED]> wrote:
>
> > From: Eric Dumazet <[EMAIL PROTECTED]>
> > Date: Fri, 16 Nov 2007 09:59:03 +0100
> >
> > > [PATCH] NET : NET_CLS_ROUTE : convert ip_rt_acct to per_cpu variables
> > >
> > > ip_rt_acct needs 4096 bytes per cpu to perform some accounting.
> > > It is actually allocated as a single huge array [4096*NR_CPUS]
> > > (rounded up to a power of two)
> > >
> > > Converting it to a per cpu variable is wanted to :
> > > - Save space on machines were num_possible_cpus() < NR_CPUS
> > > - Better NUMA placement (each cpu gets memory on its node)
> > >
> > > Signed-off-by: Eric Dumazet <[EMAIL PROTECTED]>
> >
> > This is better in one sense but worse in another.
> >
> > At least the previous code dynamically allocated the thing,
> > now at least one copy is taking up core kernel text image
> > space.
>
> Oh I see, you think that adding 4096 null bytes to the static percpu area
> might be a problem.
>
> >
> > I think it's an alloc_percpu() candidate, what do you think?
> >
>
> Yes absolutely, I will submit a new version.
>
> Thank you
[PATCH] NET : NET_CLS_ROUTE : convert ip_rt_acct to per_cpu variables
ip_rt_acct needs 4096 bytes per cpu to perform some accounting.
It is actually allocated as a single huge array [4096*NR_CPUS]
(rounded up to a power of two)
Converting it to a per cpu variable is wanted to :
- Save space on machines were num_possible_cpus() < NR_CPUS
- Better NUMA placement (each cpu gets memory on its node)
Signed-off-by: Eric Dumazet <[EMAIL PROTECTED]>
net/ipv4/ip_input.c | 2 +-
net/ipv4/route.c | 15 +++------------
2 files changed, 4 insertions(+), 13 deletions(-)
diff --git a/net/ipv4/ip_input.c b/net/ipv4/ip_input.c
index 5b8a760..4068e17 100644
--- a/net/ipv4/ip_input.c
+++ b/net/ipv4/ip_input.c
@@ -347,7 +347,7 @@ static int ip_rcv_finish(struct sk_buff *skb)
#ifdef CONFIG_NET_CLS_ROUTE
if (unlikely(skb->dst->tclassid)) {
- struct ip_rt_acct *st = ip_rt_acct + 256*smp_processor_id();
+ struct ip_rt_acct *st = per_cpu_ptr(ip_rt_acct,
smp_processor_id());
u32 idx = skb->dst->tclassid;
st[idx&0xFF].o_packets++;
st[idx&0xFF].o_bytes+=skb->len;
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 70529a9..856807c 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -2855,12 +2855,10 @@ ctl_table ipv4_route_table[] = {
#endif
#ifdef CONFIG_NET_CLS_ROUTE
-struct ip_rt_acct *ip_rt_acct;
-
-/* This code sucks. But you should have seen it before! --RR */
+struct ip_rt_acct *ip_rt_acct __read_mostly;
/* IP route accounting ptr for this logical cpu number. */
-#define IP_RT_ACCT_CPU(i) (ip_rt_acct + i * 256)
+#define IP_RT_ACCT_CPU(cpu) (per_cpu_ptr(ip_rt_acct, cpu))
#ifdef CONFIG_PROC_FS
static int ip_rt_acct_read(char *buffer, char **start, off_t offset,
@@ -2920,16 +2918,9 @@ int __init ip_rt_init(void)
(jiffies ^ (jiffies >> 7)));
#ifdef CONFIG_NET_CLS_ROUTE
- {
- int order;
- for (order = 0;
- (PAGE_SIZE << order) < 256 * sizeof(struct ip_rt_acct) * NR_CPUS;
order++)
- /* NOTHING */;
- ip_rt_acct = (struct ip_rt_acct *)__get_free_pages(GFP_KERNEL, order);
+ ip_rt_acct = __alloc_percpu(256 * sizeof(struct ip_rt_acct));
if (!ip_rt_acct)
panic("IP: failed to allocate ip_rt_acct\n");
- memset(ip_rt_acct, 0, PAGE_SIZE << order);
- }
#endif
ipv4_dst_ops.kmem_cachep =
-
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