公开(公告)号：US5617556A

公开(公告)日：1997-04-01

申请号：US515797

申请日：1995-08-16

申请人： Yoanna Baumgartner ,  Dennis G. Gregoire ,  Amy M. Youngs

发明人： Yoanna Baumgartner ,  Dennis G. Gregoire ,  Amy M. Youngs

IPC分类号： G06F12/08 ,  G06F12/00 ,  G06F13/00

CPC分类号： G06F12/0835

摘要： A system and method are provided which include devices implementing a snooping protocol. Data to be written by an I/O peripheral to an I/O controller is mapped to a specific location in memory, and then the data is actually written to an L1 cache in the controller by the I/O device. During this period when the I/O device is writing to the controller cache, the controller does not actually own the data stored in the specific memory location. Once the write operation is complete for a given memory sector, the I/O controller then performs the bus operations required to obtain ownership of the data in the specified memory location. The data read from memory is then merged with the data written from the I/O device and written back to the memory. If a snoop hit is identified by the I/O controller, during the period when the data is owned the I/O controller intervenes to prevent the memory access which caused the snoop hit. The invention limits the time period in which a snoop hit can occur to only those times when the device owning the data is already in the process of performing an atomic Read-Modify-Write operation such that reordering of queued bus transaction operations is never required.

摘要翻译： 提供了一种包括实现窥探协议的设备的系统和方法。 要由I / O控制器的I / O外设写入的数据映射到存储器中的特定位置，然后数据实际上由I / O设备写入控制器中的L1高速缓存。 在I / O设备写入控制器高速缓存期间，控制器实际上并不拥有存储在特定存储器位置的数据。 一旦写入操作对于给定的存储器扇区完成，则I / O控制器然后执行所需的总线操作以获得指定存储器位置中的数据的所有权。 然后将从存储器读取的数据与从I / O设备写入的数据合并并写入存储器。 如果I / O控制器识别出窥探命中，则在数据拥有期间，I / O控制器进行干预，以防止导致窥探命中的内存访问。 本发明将窥探命中的时间段限制在只有当拥有数据的设备已经在执行原子读 - 修改 - 写操作的过程中才能发生的时间周期，从而不需要重新排列排队的总线事务操作。

公开(公告)号：US5526512A

公开(公告)日：1996-06-11

申请号：US123820

申请日：1993-09-20

申请人： Ravi K. Arimilli ,  Dennis G. Gregoire ,  Amy M. Youngs

发明人： Ravi K. Arimilli ,  Dennis G. Gregoire ,  Amy M. Youngs

IPC分类号： G06F12/08 ,  G06F13/00

CPC分类号： G06F12/0835

摘要： A system and method dynamically changes the snoop comparison granularity between a sector and a page, depending upon the state (active or inactive) of a direct memory access (DMA) I/O device which is writing to a device on the system bus asynchronously when compared to the CPU clock. By using page address granularity, erroneous snoop hits will not occur, since potentially invalid sector addresses are not used during the snoop comparison. Sector memory addresses may be in a transition state at the time when the CPU clock determines a snoop comparison is to occur, because this sector address has been requested by a device operating asynchronously with the CPU clock. Once the asynchronous device becomes inactive the system dynamically returns to a page and sector address snoop comparison granularity.

摘要翻译： 系统和方法根据正在向系统总线上的设备异步写入的直接存储器访问（DMA）I / O设备的状态（活动或不活动）动态地改变扇区和页面之间的窥探比较粒度， 与CPU时钟相比。 通过使用页面地址粒度，将不会发生错误的窥探命中，因为在窥探比较期间不会使用潜在的无效扇区地址。 扇区存储器地址可能在CPU时钟确定侦听比较时发生转换状态，因为该扇区地址已被与CPU时钟异步运行的设备请求。 一旦异步设备变为非活动状态，系统将动态地返回到页面和扇区地址窥探比较粒度。