Uncore Manual

Reference Number: 329468-002 187
Uncore Performance Monitoring
R3QPI Performance Monitoring
VN1_CREDITS_REJECT
• Title: VN1 Credit Acquisition Failed on DRS
• Category: LINK_VN1_CREDITS Events
• Event Code: 0x39
• Max. Inc/Cyc:. 1, Register Restrictions: 0-1
• Definition: Number of times a request failed to acquire a VN1 credit. In order for a request to be
transferred across QPI, it must be guaranteed to have a flit buffer on the remote socket to sink
into. There are two credit pools, VNA and VN1. VNA is a shared pool used to achieve high perfor-
mance. The VN1 pool has reserved entries for each message class and is used to prevent dead-
lock. Requests first attempt to acquire a VNA credit, and then fall back to VN1 if they fail. This
therefore counts the number of times when a request failed to acquire either a VNA or VN1 credit
and is delayed. This should generally be a rare situation.
DRS bxxxx1xxx DRS Message Class
Filter for Data Response (DRS). DRS is generally used to
transmit data with coherency. For example, remote reads and
writes, or cache to cache transfers will transmit their data using
DRS.
NCB bxxx1xxxx NCB Message Class
Filter for Non-Coherent Broadcast (NCB). NCB is generally used
to transmit data without coherency. For example, non-coherent
read data returns.
NCS bxx1xxxxx NCS Message Class
Filter for Non-Coherent Standard (NCS). NCS is commonly used
for
Table 2-212. Unit Masks for VN1_CREDITS_REJECT
Extension
umask
[15:8]
Description
HOM bxxxxxxx1 HOM Message Class
Filter for the Home (HOM) message class. HOM is generally used
to send requests, request responses, and snoop responses.
SNP bxxxxxx1x SNP Message Class
Filter for Snoop (SNP) message class. SNP is used for outgoing
snoops. Note that snoop responses flow on the HOM message
class.
NDR bxxxxx1xx NDR Message Class
NDR packets are used to transmit a variety of protocol flits
including grants and completions (CMP).
DRS bxxxx1xxx DRS Message Class
Filter for Data Response (DRS). DRS is generally used to transmit
data with coherency. For example, remote reads and writes, or
cache to cache transfers will transmit their data using DRS.
NCB bxxx1xxxx NCB Message Class
Filter for Non-Coherent Broadcast (NCB). NCB is generally used
to transmit data without coherency. For example, non-coherent
read data returns.
NCS bxx1xxxxx NCS Message Class
Filter for Non-Coherent Standard (NCS). NCS is commonly used
for
Table 2-211. Unit Masks for VN0_CREDITS_USED
Extension
umask
[15:8]
Description