| blkif.h (288917) | blkif.h (300050) |
|---|---|
| 1/****************************************************************************** 2 * blkif.h 3 * 4 * Unified block-device I/O interface for Xen guest OSes. 5 * 6 * Permission is hereby granted, free of charge, to any person obtaining a copy 7 * of this software and associated documentation files (the "Software"), to 8 * deal in the Software without restriction, including without limitation the --- 310 unchanged lines hidden (view full) --- 319 * Default Value: 0 320 * Notes: 7, 8, 9 321 * 322 * A value of "1" indicates that the frontend will reuse the same grants 323 * for all transactions, allowing the backend to map them with write 324 * access (even when it should be read-only). If the frontend hits the 325 * maximum number of allowed persistently mapped grants, it can fallback 326 * to non persistent mode. This will cause a performance degradation, | 1/****************************************************************************** 2 * blkif.h 3 * 4 * Unified block-device I/O interface for Xen guest OSes. 5 * 6 * Permission is hereby granted, free of charge, to any person obtaining a copy 7 * of this software and associated documentation files (the "Software"), to 8 * deal in the Software without restriction, including without limitation the --- 310 unchanged lines hidden (view full) --- 319 * Default Value: 0 320 * Notes: 7, 8, 9 321 * 322 * A value of "1" indicates that the frontend will reuse the same grants 323 * for all transactions, allowing the backend to map them with write 324 * access (even when it should be read-only). If the frontend hits the 325 * maximum number of allowed persistently mapped grants, it can fallback 326 * to non persistent mode. This will cause a performance degradation, |
| 327 * since the the backend driver will still try to map those grants | 327 * since the backend driver will still try to map those grants |
| 328 * persistently. Since the persistent grants protocol is compatible with 329 * the previous protocol, a frontend driver can choose to work in 330 * persistent mode even when the backend doesn't support it. 331 * 332 * It is recommended that the frontend driver stores the persistently 333 * mapped grants in a LIFO queue, so a subset of all persistently mapped 334 * grants gets used commonly. This is done in case the backend driver 335 * decides to limit the maximum number of persistently mapped grants --- 311 unchanged lines hidden --- | 328 * persistently. Since the persistent grants protocol is compatible with 329 * the previous protocol, a frontend driver can choose to work in 330 * persistent mode even when the backend doesn't support it. 331 * 332 * It is recommended that the frontend driver stores the persistently 333 * mapped grants in a LIFO queue, so a subset of all persistently mapped 334 * grants gets used commonly. This is done in case the backend driver 335 * decides to limit the maximum number of persistently mapped grants --- 311 unchanged lines hidden --- |