公开(公告)号：US20180004663A1

公开(公告)日：2018-01-04

申请号：US15196266

申请日：2016-06-29

Applicant: ARM Limited

Inventor： Jamshed JALAL ,  Mark David WERKHEISER

IPC: G06F12/0831 ,  G06F12/084 ,  G06F12/0811 ,  G06F12/0842

CPC classification number: G06F12/0831 ,  G06F12/0811 ,  G06F12/084 ,  G06F12/0842 ,  G06F2212/1032 ,  G06F2212/6042

Abstract: A data processing system includes a snoop filter organized as a number of lines, each storing an address tag associated with the address of data stored in one or more caches of the system, a coherency state of the data, and presence data. A snoop controller sends snoop messages in response to data access requests. The presence data is configurable in a first format, in which the value of a bit in the presence data is indicative of a subset of the nodes for which at least one node in the subset has a copy of the data in its local cache, and in a second format, in which the presence data comprises a unique identifier of a node having a copy of the data in its local cache. The snoop controller sends snoop messages to the nodes indicated by the presence data.

公开(公告)号：US20170168939A1

公开(公告)日：2017-06-15

申请号：US14965131

申请日：2015-12-10

Applicant: ARM Limited

Inventor： Jamshed JALAL ,  Mark David WERKHEISER

IPC: G06F12/08

CPC classification number: G06F12/0815 ,  G06F12/0833 ,  G06F2212/1024 ,  G06F2212/1044 ,  G06F2212/621

Abstract: A data processing system, having two or more of processors that access a shared data resource, and method of operation thereof. Data stored in a local cache is marked as being in a ‘UniqueDirty’, ‘SharedDirty’, ‘UniqueClean’, ‘SharedClean’ or ‘Invalid’ state. A snoop filter monitors access by the processors to the shared data resource, and includes snoop filter control logic and a snoop filter cache configured to maintain cache coherency. The snoop filter cache does not identify any local cache that stores the block of data in a ‘SharedDirty’ state, resulting in a smaller snoop filter cache size and simple snoop control logic. The data processing system by be defined by instructions of a Hardware Description Language.

公开(公告)号：US20160062889A1

公开(公告)日：2016-03-03

申请号：US14468536

申请日：2014-08-26

Applicant: ARM Limited

Inventor： Sean James SALISBURY ,  Andrew David TUNE ,  Jamshed JALAL ,  Mark David WERKHEISER

IPC: G06F12/08

CPC classification number: G06F12/0833 ,  G06F12/0831 ,  G06F2212/1016

Abstract: An interconnect has coherency control circuitry for performing coherency control operations and a snoop filter for identifying which devices coupled to the interconnect have cached data from a given address. When an address is looked up in the snoop filter and misses, and there is no spare snoop filter entry available, then the snoop filter selects a victim entry corresponding to a victim address, and issues an invalidate transaction for invalidating locally cached copies of the data identified by the victim. The coherency control circuitry for performing coherency checking operations for data access transactions is reused for performing coherency control operations for the invalidate transaction issued by the snoop filter. This greatly reduces the circuitry complexity of the snoop filter.