[Differential] [Request, 136 lines] D5074: hyperv/hn: Improve sending performance

[sepherosa_gmail.com (Sepherosa Ziehau)]

sepherosa_gmail.com created this revision.
sepherosa_gmail.com added reviewers: network, adrian, delphij, royger, decui_microsoft.com, honzhan_microsoft.com, howard0su_gmail.com.
sepherosa_gmail.com added a subscriber: freebsd-net-list.

REVISION SUMMARY
  - Avoid main lock contention by trylock for if_start, if that fails, schedule TX taskqueue for if_start
  - Don't do direct sending if the packet to be sent is large, e.g. TSO packet.
  
  This change gives me stable 9.1Gbps TCP sending performance w/ TSO over a 10Gbe directly connected network (the performance fluctuated between 4Gbps and 9Gbps before this commit).  It also improves non-TSO TCP sending performance a lot.

REVISION DETAIL
  https://reviews.freebsd.org/D5074

AFFECTED FILES
  sys/dev/hyperv/netvsc/hv_net_vsc.h
  sys/dev/hyperv/netvsc/hv_netvsc_drv_freebsd.c

EMAIL PREFERENCES
  https://reviews.freebsd.org/settings/panel/emailpreferences/

To: sepherosa_gmail.com, network, adrian, delphij, royger, decui_microsoft.com, honzhan_microsoft.com, howard0su_gmail.com
Cc: freebsd-net-list
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