John Fastabend <john.fastabend@xxxxxxxxx> writes:
> Toke Høiland-Jørgensen wrote:
>> From: Toke Høiland-Jørgensen <toke@xxxxxxxxxx>
>>
>> Commit 96360004b862 ("xdp: Make devmap flush_list common for all map
>> instances"), changed devmap flushing to be a global operation instead of a
>> per-map operation. However, the queue structure used for bulking was still
>> allocated as part of the containing map.
>>
>> This patch moves the devmap bulk queue into struct net_device. The
>> motivation for this is reusing it for the non-map variant of XDP_REDIRECT,
>> which will be changed in a subsequent commit. To avoid other fields of
>> struct net_device moving to different cache lines, we also move a couple of
>> other members around.
>>
>> We defer the actual allocation of the bulk queue structure until the
>> NETDEV_REGISTER notification devmap.c. This makes it possible to check for
>> ndo_xdp_xmit support before allocating the structure, which is not possible
>> at the time struct net_device is allocated. However, we keep the freeing in
>> free_netdev() to avoid adding another RCU callback on NETDEV_UNREGISTER.
>>
>> Because of this change, we lose the reference back to the map that
>> originated the redirect, so change the tracepoint to always return 0 as the
>> map ID and index. Otherwise no functional change is intended with this
>> patch.
>>
>> Acked-by: Björn Töpel <bjorn.topel@xxxxxxxxx>
>> Signed-off-by: Toke Høiland-Jørgensen <toke@xxxxxxxxxx>
>> ---
>
> LGTM. I didn't check the net_device layout with pahole though so I'm
> trusting they are good from v1 discussion.
I believe so; looks like this now:
/* --- cacheline 14 boundary (896 bytes) --- */
struct netdev_queue * _tx __attribute__((__aligned__(64))); /* 896 8 */
unsigned int num_tx_queues; /* 904 4 */
unsigned int real_num_tx_queues; /* 908 4 */
struct Qdisc * qdisc; /* 912 8 */
unsigned int tx_queue_len; /* 920 4 */
spinlock_t tx_global_lock; /* 924 4 */
struct xdp_dev_bulk_queue * xdp_bulkq; /* 928 8 */
struct xps_dev_maps * xps_cpus_map; /* 936 8 */
struct xps_dev_maps * xps_rxqs_map; /* 944 8 */
struct mini_Qdisc * miniq_egress; /* 952 8 */
/* --- cacheline 15 boundary (960 bytes) --- */
struct hlist_head qdisc_hash[16]; /* 960 128 */
/* --- cacheline 17 boundary (1088 bytes) --- */
struct timer_list watchdog_timer; /* 1088 40 */
/* XXX last struct has 4 bytes of padding */
int watchdog_timeo; /* 1128 4 */
/* XXX 4 bytes hole, try to pack */
int * pcpu_refcnt; /* 1136 8 */
struct list_head todo_list; /* 1144 16 */
/* --- cacheline 18 boundary (1152 bytes) was 8 bytes ago --- */
-Toke
