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Date: Mon, 12 Sep 2016 15:57:52 -0300
From: Marcelo <marcelo.leitner@...il.com>
To: Jia He <hejianet@...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
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..
>
> 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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