Huawei S5328C Switch priority qos question

1. The trust command in ingress port will clarify different priority traffic according to 8021p or dscp, it will take effect when traffic transmit from egress port.

2. High utilization/bursts(exceed the line-rate of interface) will cause traffic drop, "display qos queue length interface " can show the max length of every queue of interface.

the input traffic on 10Gbit interface is very low ~500mbits so it outputs on Ethtrunk which is 2x1Gb. And the lots of discards on both 1gb ports occurs. So why it happens if the traffic utilization is low. As i know this type of switch have common switchfabric for all interfaces (even 10gbit). So it shouldnt be because of 10gb port which could (would) process traffic faster than gbit ports could output ?

here is some diagnostic information:

<Huawei_Switch>display qos port statistics interface GigabitEthernet 0/0/24
Port: GigabitEthernet0/0/24
-----------------------------------------------------------------------------
Queue                     Passed(Packet)                  Dropped(Packet)
-----------------------------------------------------------------------------
0                         272398                          0
-----------------------------------------------------------------------------
1                         2711934044                      971348
-----------------------------------------------------------------------------
2                         2335990                         0
-----------------------------------------------------------------------------
3                         683479622                       0
-----------------------------------------------------------------------------
4                         129725078                       0
-----------------------------------------------------------------------------
5                         2609697872                      3366
-----------------------------------------------------------------------------
6                         116700                          0
-----------------------------------------------------------------------------
7                         13706                           0
-----------------------------------------------------------------------------


InUti/OutUti: input utility/output utility
Interface                   PHY   Protocol InUti OutUti   inErrors  outErrors
Eth-Trunk1                  up    up         11%    31%          0          0
  GigabitEthernet0/0/23     up    up         10%    34%          0          0
  GigabitEthernet0/0/24     up    up         12%    29%          0          0

XGigabitEthernet0/1/2       up    up       6.25%  2.25%          0          0

<Huawei_Switch>display  interface GigabitEthernet 0/0/23 | include Discard
Discard        :                   0, Total Error        :                   0
Discard        :            23782489, Total Error        :                   0

<Huawei_Switch>display interface GigabitEthernet 0/0/24 | include Discard
Discard        :                   0, Total Error        :                   0
Discard        :            25536802, Total Error        :                   0


S5328C-EI-24S