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Date: Wed, 14 Sep 2016 11:10:19 +0800
From: hejianet <hejianet@...il.com>
To: Marcelo <marcelo.leitner@...il.com>
Cc: netdev@...r.kernel.org, linux-sctp@...r.kernel.org,
linux-kernel@...r.kernel.org, davem@...emloft.net,
Alexey Kuznetsov <kuznet@....inr.ac.ru>,
James Morris <jmorris@...ei.org>,
Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
Patrick McHardy <kaber@...sh.net>,
Vlad Yasevich <vyasevich@...il.com>,
Neil Horman <nhorman@...driver.com>,
Steffen Klassert <steffen.klassert@...unet.com>,
Herbert Xu <herbert@...dor.apana.org.au>
Subject: Re: [RFC PATCH v3 2/7] proc: Reduce cache miss in
{snmp,netstat}_seq_show
Hi Marcelo
On 9/13/16 2:57 AM, Marcelo wrote:
> On Fri, Sep 09, 2016 at 02:33:57PM +0800, Jia He wrote:
>> This is to use the generic interface snmp_get_cpu_field{,64}_batch to
>> aggregate the data by going through all the items of each cpu sequentially.
>> Then snmp_seq_show and netstat_seq_show are split into 2 parts to avoid build
>> warning "the frame size" larger than 1024 on s390.
> Yeah about that, did you test it with stack overflow detection?
> These arrays can be quite large.
>
> One more below..
I found scripts/checkstack.pl could analyze the stack usage statically.
[root@...n-lp1 kernel]# objdump -d vmlinux | scripts/checkstack.pl ppc64|grep seq
0xc0000000007d4b18 netstat_seq_show_tcpext.isra.7 [vmlinux]:1120
0xc0000000007ccbe8 fib_triestat_seq_show [vmlinux]: 496
0xc00000000083e7a4 tcp6_seq_show [vmlinux]: 480
0xc0000000007d4908 snmp_seq_show_ipstats.isra.6 [vmlinux]:464
0xc0000000007d4d18 netstat_seq_show_ipext.isra.8 [vmlinux]:464
0xc0000000006f5bd8 proto_seq_show [vmlinux]: 416
0xc0000000007f5718 xfrm_statistics_seq_show [vmlinux]: 416
0xc0000000007405b4 dev_seq_printf_stats [vmlinux]: 400
seems the stack usage in netstat_seq_show_tcpext is too big.
Will consider how to reduce it
B.R.
Jia
>> Signed-off-by: Jia He <hejianet@...il.com>
>> ---
>> net/ipv4/proc.c | 106 +++++++++++++++++++++++++++++++++++++++-----------------
>> 1 file changed, 74 insertions(+), 32 deletions(-)
>>
>> diff --git a/net/ipv4/proc.c b/net/ipv4/proc.c
>> index 9f665b6..c6fc80e 100644
>> --- a/net/ipv4/proc.c
>> +++ b/net/ipv4/proc.c
>> @@ -46,6 +46,8 @@
>> #include <net/sock.h>
>> #include <net/raw.h>
>>
>> +#define TCPUDP_MIB_MAX max_t(u32, UDP_MIB_MAX, TCP_MIB_MAX)
>> +
>> /*
>> * Report socket allocation statistics [mea@....fi]
>> */
>> @@ -378,13 +380,15 @@ static void icmp_put(struct seq_file *seq)
>> /*
>> * Called from the PROCfs module. This outputs /proc/net/snmp.
>> */
>> -static int snmp_seq_show(struct seq_file *seq, void *v)
>> +static int snmp_seq_show_ipstats(struct seq_file *seq, void *v)
>> {
>> int i;
>> + u64 buff64[IPSTATS_MIB_MAX];
>> struct net *net = seq->private;
>>
>> - seq_puts(seq, "Ip: Forwarding DefaultTTL");
>> + memset(buff64, 0, IPSTATS_MIB_MAX * sizeof(u64));
>>
>> + seq_puts(seq, "Ip: Forwarding DefaultTTL");
>> for (i = 0; snmp4_ipstats_list[i].name != NULL; i++)
>> seq_printf(seq, " %s", snmp4_ipstats_list[i].name);
>>
>> @@ -393,57 +397,77 @@ static int snmp_seq_show(struct seq_file *seq, void *v)
>> net->ipv4.sysctl_ip_default_ttl);
>>
>> BUILD_BUG_ON(offsetof(struct ipstats_mib, mibs) != 0);
>> + snmp_get_cpu_field64_batch(buff64, snmp4_ipstats_list,
>> + net->mib.ip_statistics,
>> + offsetof(struct ipstats_mib, syncp));
>> for (i = 0; snmp4_ipstats_list[i].name != NULL; i++)
>> - seq_printf(seq, " %llu",
>> - snmp_fold_field64(net->mib.ip_statistics,
>> - snmp4_ipstats_list[i].entry,
>> - offsetof(struct ipstats_mib, syncp)));
>> + seq_printf(seq, " %llu", buff64[i]);
>>
>> - icmp_put(seq); /* RFC 2011 compatibility */
>> - icmpmsg_put(seq);
>> + return 0;
>> +}
>> +
>> +static int snmp_seq_show_tcp_udp(struct seq_file *seq, void *v)
>> +{
>> + int i;
>> + unsigned long buff[TCPUDP_MIB_MAX];
>> + struct net *net = seq->private;
>> +
>> + memset(buff, 0, TCPUDP_MIB_MAX * sizeof(unsigned long));
>>
>> seq_puts(seq, "\nTcp:");
>> for (i = 0; snmp4_tcp_list[i].name != NULL; i++)
>> seq_printf(seq, " %s", snmp4_tcp_list[i].name);
>>
>> seq_puts(seq, "\nTcp:");
>> + snmp_get_cpu_field_batch(buff, snmp4_tcp_list,
>> + net->mib.tcp_statistics);
>> for (i = 0; snmp4_tcp_list[i].name != NULL; i++) {
>> /* MaxConn field is signed, RFC 2012 */
>> if (snmp4_tcp_list[i].entry == TCP_MIB_MAXCONN)
>> - seq_printf(seq, " %ld",
>> - snmp_fold_field(net->mib.tcp_statistics,
>> - snmp4_tcp_list[i].entry));
>> + seq_printf(seq, " %ld", buff[i]);
>> else
>> - seq_printf(seq, " %lu",
>> - snmp_fold_field(net->mib.tcp_statistics,
>> - snmp4_tcp_list[i].entry));
>> + seq_printf(seq, " %lu", buff[i]);
>> }
>>
>> + memset(buff, 0, TCPUDP_MIB_MAX * sizeof(unsigned long));
>> +
>> + snmp_get_cpu_field_batch(buff, snmp4_udp_list,
>> + net->mib.udp_statistics);
>> seq_puts(seq, "\nUdp:");
>> for (i = 0; snmp4_udp_list[i].name != NULL; i++)
>> seq_printf(seq, " %s", snmp4_udp_list[i].name);
>> -
>> seq_puts(seq, "\nUdp:");
>> for (i = 0; snmp4_udp_list[i].name != NULL; i++)
>> - seq_printf(seq, " %lu",
>> - snmp_fold_field(net->mib.udp_statistics,
>> - snmp4_udp_list[i].entry));
>> + seq_printf(seq, " %lu", buff[i]);
>> +
>> + memset(buff, 0, TCPUDP_MIB_MAX * sizeof(unsigned long));
>>
>> /* the UDP and UDP-Lite MIBs are the same */
>> seq_puts(seq, "\nUdpLite:");
>> + snmp_get_cpu_field_batch(buff, snmp4_udp_list,
>> + net->mib.udplite_statistics);
>> for (i = 0; snmp4_udp_list[i].name != NULL; i++)
>> seq_printf(seq, " %s", snmp4_udp_list[i].name);
>> -
>> seq_puts(seq, "\nUdpLite:");
>> for (i = 0; snmp4_udp_list[i].name != NULL; i++)
>> - seq_printf(seq, " %lu",
>> - snmp_fold_field(net->mib.udplite_statistics,
>> - snmp4_udp_list[i].entry));
>> + seq_printf(seq, " %lu", buff[i]);
>>
>> seq_putc(seq, '\n');
>> return 0;
>> }
>>
>> +static int snmp_seq_show(struct seq_file *seq, void *v)
>> +{
>> + snmp_seq_show_ipstats(seq, v);
>> +
>> + icmp_put(seq); /* RFC 2011 compatibility */
>> + icmpmsg_put(seq);
>> +
>> + snmp_seq_show_tcp_udp(seq, v);
>> +
>> + return 0;
>> +}
>> +
>> static int snmp_seq_open(struct inode *inode, struct file *file)
>> {
>> return single_open_net(inode, file, snmp_seq_show);
>> @@ -457,41 +481,59 @@ static const struct file_operations snmp_seq_fops = {
>> .release = single_release_net,
>> };
>>
>> -
>> -
>> /*
>> * Output /proc/net/netstat
>> */
>> -static int netstat_seq_show(struct seq_file *seq, void *v)
>> +static int netstat_seq_show_tcpext(struct seq_file *seq, void *v)
>> {
>> int i;
>> + unsigned long buff[LINUX_MIB_MAX];
>> struct net *net = seq->private;
>>
>> + memset(buff, 0, sizeof(unsigned long) * LINUX_MIB_MAX);
>> +
>> seq_puts(seq, "TcpExt:");
>> for (i = 0; snmp4_net_list[i].name != NULL; i++)
>> seq_printf(seq, " %s", snmp4_net_list[i].name);
>>
>> seq_puts(seq, "\nTcpExt:");
>> + snmp_get_cpu_field_batch(buff, snmp4_net_list,
>> + net->mib.net_statistics);
>> for (i = 0; snmp4_net_list[i].name != NULL; i++)
>> - seq_printf(seq, " %lu",
>> - snmp_fold_field(net->mib.net_statistics,
>> - snmp4_net_list[i].entry));
>> + seq_printf(seq, " %lu", buff[i]);
>> +
>> + return 0;
>> +}
>> +
>> +static int netstat_seq_show_ipext(struct seq_file *seq, void *v)
>> +{
>> + int i;
>> + u64 buff64[IPSTATS_MIB_MAX];
>> + struct net *net = seq->private;
>>
>> seq_puts(seq, "\nIpExt:");
>> for (i = 0; snmp4_ipextstats_list[i].name != NULL; i++)
>> seq_printf(seq, " %s", snmp4_ipextstats_list[i].name);
>>
>> seq_puts(seq, "\nIpExt:");
> You're missing a memset() call here.
>
>> + snmp_get_cpu_field64_batch(buff64, snmp4_ipextstats_list,
>> + net->mib.ip_statistics,
>> + offsetof(struct ipstats_mib, syncp));
>> for (i = 0; snmp4_ipextstats_list[i].name != NULL; i++)
>> - seq_printf(seq, " %llu",
>> - snmp_fold_field64(net->mib.ip_statistics,
>> - snmp4_ipextstats_list[i].entry,
>> - offsetof(struct ipstats_mib, syncp)));
>> + seq_printf(seq, " %llu", buff64[i]);
>>
>> seq_putc(seq, '\n');
>> return 0;
>> }
>>
>> +static int netstat_seq_show(struct seq_file *seq, void *v)
>> +{
>> + netstat_seq_show_tcpext(seq, v);
>> + netstat_seq_show_ipext(seq, v);
>> +
>> + return 0;
>> +}
>> +
>> static int netstat_seq_open(struct inode *inode, struct file *file)
>> {
>> return single_open_net(inode, file, netstat_seq_show);
>> --
>> 1.8.3.1
>>
>> --
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