摘要:
Fine-grained detection of data modification of original data is provided by associating separate guard bits with granules of memory storing original data from which translated data has been obtained. The guard bits indicating whether the original data stored in the associated granule is protected for data coherency. The guard bits are set and cleared by special-purpose instructions. Responsive to attempting access to translated data obtained from the original data, the guard bit(s) associated with the original data is checked to determine whether the guard bit(s) fail to indicate coherency of the original data, and if so, discarding of the translated data is initiated to facilitate maintaining data coherency between the original data and the translated data.
摘要:
A method is provided for fine-grained detection of data modification of original data by associating separate guard bits with granules of memory storing original data from which translated data has been obtained. The guard bits indicating whether the original data stored in the associated granule is protected for data coherency. The guard bits are set and cleared by special-purpose instructions. Responsive to attempting access to translated data obtained from the original data, the guard bit(s) associated with the original data is checked to determine whether the guard bit(s) fail to indicate coherency of the original data, and if so, discarding of the translated data is initiated to facilitate maintaining data coherency between the original data and the translated data.
摘要:
Fine-grained detection of data modification of original data is provided by associating separate guard bits with granules of memory storing the original data from which translated data has been obtained. The guard bits facilitate indicating whether the original data stored in the associated granule is indicated as protected. The guard bits are set and cleared by special-purpose instructions. Responsive to initiating a data store operation to modify the original data, the associated guard bit(s) are checked to determine whether the original data is indicated as protected. Responsive to the checking indicating that a guard bit is set for the associated original data, the data store operation to modify the original data is faulted and the translated data is discarded, thereby facilitating data coherency between the original data and the translated data.
摘要:
A method, system, and computer program product enhances resource/process availability by providing hardware based buffering of network packets during checkpointing in a virtualized environment. A High Availability Checkpoint (HAC) utility pre-configures a physical network adapter to buffer outgoing network packets from virtual machines that employ a checkpointing technology. In response to receiving an outgoing network packet from a virtual machine and determining that the virtual machine employs a pre-specified checkpointing technology, the physical network adapter buffers the outgoing network packet. In addition, a primary host performs/facilitates checkpoint operations (associated with the virtual machine) with a secondary host. When checkpoint operations are successfully completed, the HAC utility triggers the transmission of the buffered network packets from the network adapter to a network destination. The physical network adapter minimizes checkpointing network latency by pre-assigning a higher priority to a buffered network packet from a checkpointing virtual machine than to a new network packet that originates from a non-checkpointing virtual machine.
摘要:
A computer-implemented method, computer program product and data processing system provide checkpoint high-available for an application in a virtualized environment with reduced network demands. An application executes on a primary host machine comprising a first virtual machine. A virtualization module receives a designation from the application of a portion of the memory of the first virtual machine as purgeable memory, wherein the purgeable memory can be reconstructed by the application when the purgeable memory is unavailable. Changes are tracked to a processor state and to a remaining portion that is not purgeable memory and the changes are periodically forwarded at checkpoints to a secondary host machine. In response to an occurrence of a failure condition on the first virtual machine, the secondary host machine is signaled to continue execution of the application by using the forwarded changes to the remaining portion of the memory and by reconstructing the purgeable memory.
摘要:
Performing storage writes in a mirrored virtual machine system by receiving a state of a primary virtual machine during execution of an application, wherein the primary virtual machine runs on a first physical machine and a secondary virtual machine runs on a second physical machine, wherein the state is captured by checkpointing, and the primary virtual machine is configured to write data to a first block and concurrently write the data to a write buffer on the secondary virtual machine. The method also includes storing a copy of data within a second block to a rollback buffer for the secondary virtual machine, in response to identifying a checkpoint in the application, merging the rollback buffer with the write buffer, in response to detecting a failover, writing a copy of the rollback buffer to the disk storage, and continuing execution on the secondary virtual machine from the last checkpoint.
摘要:
In program code conversion, particularly dynamic binary translation, subject code 17 is translated into target code 21 through a translator 19 for execution on a target processor 13. Selected portions of subject code, such as library functions SFuncA 172, are replaced by instead executing a portion of native code such as a native function NFuncA 282. The native function is native to the target processor 13. The method further includes executing a subject code portion such as a subject function SFuncB 173 in place of a native code portion such library function NFuncB 283. This reverse binding technique substitutes subject code for selected portions of the native code, particularly native library functions in order to keep control within the translator 19. This helps to maintain an accurate subject state in the translator 19, amongst other advantages.
摘要:
An emulator (30) allows subject code (10) written for a subject processor (12) having subject processor registers (14) and condition code flags (16) to run in a non-compatible computing environment (2). The emulator (30) identifies and records parameters of instructions in the subject code (10) that affect status of the subject condition code flags (16). Then, when an instruction in the subject code (10) is encountered, such as a branch or jump, that uses the flag status to make a decision, the flag status is resolved from the recorded instruction parameters. Advantageously, emulation overhead is substantially reduced.
摘要:
Two or more processes for executing a source application are emulated using: a virtual trampoline memory in which each emulated process has a respective private trampoline memory; and a shared code heap memory. Each emulated process only sees the shared code heap and its respective private trampoline memory. A respective equivalent target instruction fragment for writing to the code heap is generated for each of multiple source instruction fragments from the application, each target instruction fragment being indexed by its physical address in the code heap. Each of at least one jump instruction in the fragment is replaced with a jump to a corresponding slot in the virtual trampoline memory. A trap is written to each corresponding private trampoline slot, each trap adapted to be replaced by a jump to an address in the code heap corresponding to the jump destination.
摘要:
Performing storage writes in a mirrored virtual machine system by receiving a state of a primary virtual machine during execution of an application, wherein the primary virtual machine runs on a first physical machine and a secondary virtual machine runs on a second physical machine, wherein the state is captured by checkpointing, and the primary virtual machine is configured to write data to a first block and concurrently write the data to a write buffer on the secondary virtual machine. The method also includes storing a copy of data within a second block to a rollback buffer for the secondary virtual machine, in response to identifying a checkpoint in the application, merging the rollback buffer with the write buffer, in response to detecting a failover, writing a copy of the rollback buffer to the disk storage, and continuing execution on the secondary virtual machine from the last checkpoint.