A computer system, comprising: a processor; and a peripheral component interconnect express PCIe bus, for connecting to a PCIe endpoint device, wherein: the computer system further comprises an access proxy and the access proxy connects the processor and the PCIe endpoint device; the processor is configured to acquire an operation instruction, wherein the operation instruction instructs the processor to access the PCIe endpoint device through the access proxy; and send an access request to the access proxy according to the operation instruction, wherein the access request instructs the access proxy to access the PCIe endpoint device; and the access proxy is configured to send, after receiving the access request sent by the processor, a response message of the access request to the processor regardless of whether access to the PCIe endpoint device is successful; the processor is further configured to determine that a task corresponding to the access request is complete after receiving the response message and shut off a timer initiated for the task; the access proxy is further configured to access the PCIe endpoint device according to the access request, send a first notification message or a second notification message to the processor, wherein the first notification message indicates that access to the PCIe endpoint device is successful, the second notification message indicates that the access to the PCIe endpoint device fails; the processor is further configured to acquire an access result after receiving the first notification message, and execute subsequent processing for an access failure after receiving the second notification message. a processor; and a peripheral component interconnect express PCIe bus, for connecting to a PCIe endpoint device, wherein: the computer system further comprises an access proxy and the access proxy connects the processor and the PCIe endpoint device; the processor is configured to acquire an operation instruction, wherein the operation instruction instructs the processor to access the PCIe endpoint device through the access proxy; and send an access request to the access proxy according to the operation instruction, wherein the access request instructs the access proxy to access the PCIe endpoint device; and the access proxy is configured to send, after receiving the access request sent by the processor, a response message of the access request to the processor regardless of whether access to the PCIe endpoint device is successful; the processor is further configured to determine that a task corresponding to the access request is complete after receiving the response message and shut off a timer initiated for the task; the access proxy is further configured to access the PCIe endpoint device according to the access request, send a first notification message or a second notification message to the processor, wherein the first notification message indicates that access to the PCIe endpoint device is successful, the second notification message indicates that the access to the PCIe endpoint device fails; the processor is further configured to acquire an access result after receiving the first notification message, and execute subsequent processing for an access failure after receiving the second notification message. the computer system further comprises an access proxy and the access proxy connects the processor and the PCIe endpoint device; the processor is configured to acquire an operation instruction, wherein the operation instruction instructs the processor to access the PCIe endpoint device through the access proxy; and send an access request to the access proxy according to the operation instruction, wherein the access request instructs the access proxy to access the PCIe endpoint device; and the access proxy is configured to send, after receiving the access request sent by the processor, a response message of the access request to the processor regardless of whether access to the PCIe endpoint device is successful; the processor is further configured to determine that a task corresponding to the access request is complete after receiving the response message and shut off a timer initiated for the task; the access proxy is further configured to access the PCIe endpoint device according to the access request, send a first notification message or a second notification message to the processor, wherein the first notification message indicates that access to the PCIe endpoint device is successful, the second notification message indicates that the access to the PCIe endpoint device fails; the processor is further configured to acquire an access result after receiving the first notification message, and execute subsequent processing for an access failure after receiving the second notification message.