net: udp: correct the document for udp_mem

udp_mem is a vector of 3 INTEGERs, which is used to limit the number of
pages allowed for queueing by all UDP sockets.

However, sk_has_memory_pressure() in __sk_mem_raise_allocated() always
return false for udp, as memory pressure is not supported by udp, which
means that __sk_mem_raise_allocated() will fail once pages allocated
for udp socket exceeds udp_mem[0].

Therefor, udp_mem[0] is the only one that limit the number of pages.
However, the document of udp_mem just express that udp_mem[2] is the
limitation. So, just fix it.

Signed-off-by: Menglong Dong <imagedong@tencent.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Menglong Dong 2021-11-05 15:35:41 +08:00 committed by David S. Miller
parent 827beb7781
commit 69dfccbc11

View file

@ -1004,13 +1004,11 @@ udp_l3mdev_accept - BOOLEAN
udp_mem - vector of 3 INTEGERs: min, pressure, max
Number of pages allowed for queueing by all UDP sockets.
min: Below this number of pages UDP is not bothered about its
memory appetite. When amount of memory allocated by UDP exceeds
this number, UDP starts to moderate memory usage.
min: Number of pages allowed for queueing by all UDP sockets.
pressure: This value was introduced to follow format of tcp_mem.
max: Number of pages allowed for queueing by all UDP sockets.
max: This value was introduced to follow format of tcp_mem.
Default is calculated at boot time from amount of available memory.