Hi Ben
I am not quite getting the below error. I believe this may be coming
because of existing macro atomic_read_explicit definition.
#define atomic_read_explicit(SRC, DST, ORDER) \
(*(DST) = atomic_load_explicit(SRC, ORDER), \
(void) 0)
Where I believe it is cribbing for (void)0 which gcc is cribbing that it may
not have any effect. I have corrected the other errors.
I see some discussion of this sort in this URL.
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61081
From the discussion if I understood correctly it is a false alarm present from
gcc 4.9.
>> In file included from ../lib/ovs-atomic.h:331,
>> from ../lib/dpif-netdev-perf.h:32,
>> from ../lib/dpif-netdev-perf.c:20:
>> ../lib/dpif-netdev-perf.c: In function 'pmd_perf_drop_stats_clear':
>> ../lib/ovs-atomic-c11.h:31:47: error: right-hand operand of comma
>> expression has no effect [-Werror=unused-value]
>> (*(DST) = atomic_load_explicit(SRC, ORDER), \
>> ^
>> ../lib/ovs-atomic.h:401:5: note: in expansion of macro
>> 'atomic_read_explicit'
>> atomic_read_explicit(VAR, DST, memory_order_relaxed)
>> ^~~~~~~~~~~~~~~~~~~~
>> ../lib/dpif-netdev-perf.c:474:9: note: in expansion of macro
>> 'atomic_read_relaxed'
>> atomic_read_relaxed(&s->drop_counters.n.rx_drops[i],
>> ^~~~~~~~~~~~~~~~~~~
>> ../lib/ovs-atomic-c11.h:31:47: error: right-hand operand of comma
>> expression has no effect [-Werror=unused-value]
(*(DST) = atomic_load_explicit(SRC, ORDER), \
Thanks
Keshav
-----Original Message-----
From: Ben Pfaff [mailto:b...@ovn.org]
Sent: Saturday, September 08, 2018 1:29 AM
To: Keshav Gupta <keshav.gu...@ericsson.com>
Cc: d...@openvswitch.org; Anju Thomas <anju.tho...@ericsson.com>
Subject: Re: [ovs-dev] [PATCH v3] Improved Packet Drop Statistics in OVS
On Sat, Sep 08, 2018 at 03:00:56AM +0530, Keshav Gupta wrote:
> Currently OVS maintains explicit packet drop/error counters only on port
> level. Packets that are dropped as part of normal OpenFlow processing are
> counted in flow stats of “drop” flows or as table misses in table stats.
> These can only be interpreted by controllers that know the semantics of
> the configured OpenFlow pipeline. Without that knowledge, it is impossible
> for an OVS user to obtain e.g. the total number of packets dropped due to
> OpenFlow rules.
>
> Furthermore, there are numerous other reasons for which packets can be
> dropped by OVS slow path that are not related to the OpenFlow pipeline.
> The generated datapath flow entries include a drop action to avoid further
> expensive upcalls to the slow path, but subsequent packets dropped by the
> datapath are not accounted anywhere.
>
> Finally, the datapath itself drops packets in certain error situations.
> Also, these drops are today not accounted for.
>
> This makes it difficult for OVS users to monitor packet drop in an OVS
> instance and to alert a management system in case of a unexpected increase
> of such drops. Also OVS trouble-shooters face difficulties in analysing
> packet drops.
>
> With this patch we implement following changes to address the issues
> mentioned above.
>
> 1. Account and categorize all the packet drops in OVS.
> 2. Account & classify “drop” action packet drops according to the drop
> reason.
> 3. Identify and account all the silent packet drop scenarios.
> 4. Have new cli command to display consolidated packet drop output
> 5. Modified ovs-appctl dpcls/dump-flows and ovs-appctl dpif/dump-flows
> to print drop reason along with drop action
>
> A detailed presentation on this was presented at OvS conference 2017 and
> link for the corresponding presentation is available at:
>
> https://www.slideshare.net/LF_OpenvSwitch/lfovs17troubleshooting-the-d
> ata-plane-in-ovs-82280329
>
> Sample ovs-appctl dpcls/dump-flows & ovs-appctl dpif/dump-flows
> displaying drop reason along with drop action.
> ---------------------------------------------------------------
>
> $ ovs-appctl dpctl/dump-flows netdev@ovs-netdev
> flow-dump from pmd on cpu core: 0
>
> recirc_id(0),in_port(5),packet_type(ns=0,id=0),eth_type(0x0800),ipv4(f
> rag=no), packets:12, bytes:1176, used:0.884s, actions:drop:recursion
> too deep
>
> $ ovs-appctl dpif/dump-flows br-int
>
> recirc_id(0),in_port(5),packet_type(ns=0,id=0),eth_type(0x0800),ipv4(frag=no),
> packets:25, bytes:2450, used:5.008s, actions:drop:recursion too deep
> recirc_id(0),in_port(5),packet_type(ns=0,id=0),eth_type(0x0806),
> packets:7, bytes:294, used:0.009s, actions:drop:recursion too deep
>
> Sample drop stats summary output.
> ---------------------------------
> $ ovs-appctl dpif/show-drop-stats
> netdev:
> rx-drops :0
> dataplane-processing-drops :59
> drop action :59
> upcall drops :0
> dp error drops :0
> tx-drops :0
>
> Sample detailed drop stats output.
> ---------------------------------
> $ ovs-appctl dpif/show-drop-stats --detail
> netdev:
> rx-drops:
> [IDX] Drop Reason Packets
> ------- ------------------------------------- ------------
> 0 interface & policer 0
> 1 parsing error/invalid packet 0
> dataplane-processing-drops:
> "drop" action:
> 2 pipeline drop 0
> 3 bridge not found 0
> 4 recursion too deep 68
> 5 too many resubmits 0
> 6 stack too deep 0
> 7 no recirculation context 0
> 8 recirculation conflict 0
> 9 too many mpls labels 0
> 10 invalid tunnel metadata 0
> 11 unsupported packet type 0
> 12 ecn mismatch at tunnel decapsulation 0
> 13 forwarding disabled (stp/rstp) 0
> upcall drops:
> 14 upcall lock contention drop 0
> 15 upcall error drops 0
> dp error drops:
> 16 tunnel pop action errors 0
> 17 tunnel push action errors 0
> 18 nsh decap errors 0
> 19 recirculation errors 0
> 20 sampling error 0
> 21 meter drop 0
> 22 user space action error 0
> 23 invalid port 0
> 24 invalid tunnel port 0
> tx-drops:
> 25 interface & policer 0
>
> Drop stats clear command.
> ---------------------------------
> $ ovs-appctl dpif/clear-drop-stats
> $ ovs-appctl dpif/show-drop-stats
> netdev:
> rx-drops :0
> dataplane-processing-drops :0
> drop action :0
> upcall drops :0
> dp error drops :0
> tx-drops :0
>
> Co-authored-by: Rohith Basavaraja <rohith.basavar...@gmail.com>
> Co-authored-by: Anju Thomas <anju.tho...@ericsson.com>
> Signed-off-by: Rohith Basavaraja <rohith.basavar...@gmail.com>
> Signed-off-by: Keshav Gupta <keshav.gu...@ericsson.com>
> Signed-off-by: Anju Thomas <anju.tho...@ericsson.com>
Thanks for the patch.
Please don't indent the commit message like that. The commit message should be
at the left margin.
"Clang" says;
../ofproto/ofproto-dpif.c:5810:14: error: declaration shadows a local
variable [-Werror,-Wshadow]
../ofproto/ofproto-dpif.c:5805:9: note: previous declaration is here
../ofproto/ofproto-dpif.c:5843:66: error: unused parameter 'argv'
[-Werror,-Wunused-parameter]
Makefile:5133: recipe for target
'ofproto/ofproto_libofproto_la-ofproto-dpif.lo' failed
GCC says:
In file included from ../lib/ovs-atomic.h:331,
from ../lib/dpif-netdev-perf.h:32,
from ../lib/dpif-netdev-perf.c:20:
../lib/dpif-netdev-perf.c: In function 'pmd_perf_drop_stats_clear':
../lib/ovs-atomic-c11.h:31:47: error: right-hand operand of comma
expression has no effect [-Werror=unused-value]
(*(DST) = atomic_load_explicit(SRC, ORDER), \
^
../lib/ovs-atomic.h:401:5: note: in expansion of macro
'atomic_read_explicit'
atomic_read_explicit(VAR, DST, memory_order_relaxed)
^~~~~~~~~~~~~~~~~~~~
../lib/dpif-netdev-perf.c:474:9: note: in expansion of macro
'atomic_read_relaxed'
atomic_read_relaxed(&s->drop_counters.n.rx_drops[i],
^~~~~~~~~~~~~~~~~~~
../lib/ovs-atomic-c11.h:31:47: error: right-hand operand of comma
expression has no effect [-Werror=unused-value]
(*(DST) = atomic_load_explicit(SRC, ORDER), \
^
../lib/ovs-atomic.h:401:5: note: in expansion of macro
'atomic_read_explicit'
atomic_read_explicit(VAR, DST, memory_order_relaxed)
^~~~~~~~~~~~~~~~~~~~
../lib/dpif-netdev-perf.c:478:9: note: in expansion of macro
'atomic_read_relaxed'
atomic_read_relaxed(&s->drop_counters.n.drop_action_drops[i],
^~~~~~~~~~~~~~~~~~~
../lib/ovs-atomic-c11.h:31:47: error: right-hand operand of comma
expression has no effect [-Werror=unused-value]
(*(DST) = atomic_load_explicit(SRC, ORDER), \
^
../lib/ovs-atomic.h:401:5: note: in expansion of macro
'atomic_read_explicit'
atomic_read_explicit(VAR, DST, memory_order_relaxed)
^~~~~~~~~~~~~~~~~~~~
../lib/dpif-netdev-perf.c:482:9: note: in expansion of macro
'atomic_read_relaxed'
atomic_read_relaxed(&s->drop_counters.n.dp_drops[i],
^~~~~~~~~~~~~~~~~~~
../lib/ovs-atomic-c11.h:31:47: error: right-hand operand of comma
expression has no effect [-Werror=unused-value]
(*(DST) = atomic_load_explicit(SRC, ORDER), \
^
../lib/ovs-atomic.h:401:5: note: in expansion of macro
'atomic_read_explicit'
atomic_read_explicit(VAR, DST, memory_order_relaxed)
^~~~~~~~~~~~~~~~~~~~
../lib/dpif-netdev-perf.c:486:9: note: in expansion of macro
'atomic_read_relaxed'
atomic_read_relaxed(&s->drop_counters.n.tx_drops[i],
^~~~~~~~~~~~~~~~~~~
../ofproto/ofproto-dpif.c:5810:14: error: symbol 'i' shadows an earlier one
../ofproto/ofproto-dpif.c:5805:9: originally declared here
"sparse" says:
../ofproto/ofproto-dpif-xlate.c:456:23: error: symbol
'xlate_error_to_drop_reason' redeclared with different type (originally
declared at ../ofproto/ofproto-dpif-xlate.h:227) - different signedness
Please fix these issues and resubmit.
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