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On Sun, Mar 06, 2011 at 02:18:35PM +0200, Julian Anastasov wrote:
[ snip ]
> Zero the new percpu stats because we copy from there.
> Use the stats spin lock to synchronize the percpu zeroing with
> the percpu reading, both in user context and not in a hot path.
>
> Signed-off-by: Julian Anastasov <ja@xxxxxx>
Eric, do you have any thoughts on this?
It seems clean to me.
> ---
>
> diff -urp lvs-test-2.6-8a80c79/linux/net/netfilter/ipvs/ip_vs_ctl.c
> linux/net/netfilter/ipvs/ip_vs_ctl.c
> --- lvs-test-2.6-8a80c79/linux/net/netfilter/ipvs/ip_vs_ctl.c 2011-03-06
> 13:39:59.000000000 +0200
> +++ linux/net/netfilter/ipvs/ip_vs_ctl.c 2011-03-06 13:44:56.108275455
> +0200
> @@ -713,8 +713,25 @@ static void ip_vs_trash_cleanup(struct n
> static void
> ip_vs_zero_stats(struct ip_vs_stats *stats)
> {
> + struct ip_vs_cpu_stats *cpustats = stats->cpustats;
> + int i;
> +
> spin_lock_bh(&stats->lock);
>
> + for_each_possible_cpu(i) {
> + struct ip_vs_cpu_stats *u = per_cpu_ptr(cpustats, i);
> + unsigned int start;
> +
> + /* Do not pretend to be writer, it is enough to
> + * sync with writers that modify the u64 counters
> + * because under stats->lock there are no other readers
> + */
> + do {
> + start = u64_stats_fetch_begin(&u->syncp);
> + memset(&u->ustats, 0, sizeof(u->ustats));
> + } while (u64_stats_fetch_retry(&u->syncp, start));
> + }
> +
> memset(&stats->ustats, 0, sizeof(stats->ustats));
> ip_vs_zero_estimator(stats);
>
> @@ -2015,16 +2032,19 @@ static int ip_vs_stats_percpu_show(struc
> seq_printf(seq,
> "CPU Conns Packets Packets Bytes
> Bytes\n");
>
> + /* Use spin lock early to synchronize with percpu zeroing */
> + spin_lock_bh(&tot_stats->lock);
> +
> for_each_possible_cpu(i) {
> struct ip_vs_cpu_stats *u = per_cpu_ptr(cpustats, i);
> unsigned int start;
> __u64 inbytes, outbytes;
>
> do {
> - start = u64_stats_fetch_begin_bh(&u->syncp);
> + start = u64_stats_fetch_begin(&u->syncp);
> inbytes = u->ustats.inbytes;
> outbytes = u->ustats.outbytes;
> - } while (u64_stats_fetch_retry_bh(&u->syncp, start));
> + } while (u64_stats_fetch_retry(&u->syncp, start));
>
> seq_printf(seq, "%3X %8X %8X %8X %16LX %16LX\n",
> i, u->ustats.conns, u->ustats.inpkts,
> @@ -2032,7 +2052,6 @@ static int ip_vs_stats_percpu_show(struc
> (__u64)outbytes);
> }
>
> - spin_lock_bh(&tot_stats->lock);
> seq_printf(seq, " ~ %8X %8X %8X %16LX %16LX\n\n",
> tot_stats->ustats.conns, tot_stats->ustats.inpkts,
> tot_stats->ustats.outpkts,
>
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