hdf5.git - Mirror from: https://github.com/HDFGroup/hdf5.git

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/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * Copyright by The HDF Group. * * Copyright by the Board of Trustees of the University of Illinois. * * All rights reserved. * * * * This file is part of HDF5. The full HDF5 copyright notice, including * * terms governing use, modification, and redistribution, is contained in * * the COPYING file, which can be found at the root of the source code * * distribution tree, or in https://support.hdfgroup.org/ftp/HDF5/releases. * * If you do not have access to either file, you may request a copy from * * help@hdfgroup.org. * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */ /*------------------------------------------------------------------------- * * Created: H5ACpublic.h * Jul 10 1997 * Robb Matzke <matzke@llnl.gov> * * Purpose: Public include file for cache functions. * * Modifications: * *------------------------------------------------------------------------- */ #ifndef _H5ACpublic_H #define _H5ACpublic_H /* Public headers needed by this file */ #include "H5public.h" #include "H5Cpublic.h" #ifdef __cplusplus extern "C" { #endif /**************************************************************************** * * structure H5AC_cache_config_t * * H5AC_cache_config_t is a public structure intended for use in public APIs. * At least in its initial incarnation, it is basically a copy of struct * H5C_auto_size_ctl_t, minus the report_fcn field, and plus the * dirty_bytes_threshold field. * * The report_fcn field is omitted, as including it would require us to * make H5C_t structure public. * * The dirty_bytes_threshold field does not appear in H5C_auto_size_ctl_t, * as synchronization between caches on different processes is handled at * the H5AC level, not at the level of H5C. Note however that there is * considerable interaction between this value and the other fields in this * structure. * * Similarly, the open_trace_file, close_trace_file, and trace_file_name * fields do not appear in H5C_auto_size_ctl_t, as most trace file * issues are handled at the H5AC level. The one exception is storage of * the pointer to the trace file, which is handled by H5C. * * The structure is in H5ACpublic.h as we may wish to allow different * configuration options for metadata and raw data caches. * * The fields of the structure are discussed individually below: * * version: Integer field containing the version number of this version * of the H5AC_cache_config_t structure. Any instance of * H5AC_cache_config_t passed to the cache must have a known * version number, or an error will be flagged. * * rpt_fcn_enabled: Boolean field used to enable and disable the default * reporting function. This function is invoked every time the * automatic cache resize code is run, and reports on its activities. * * This is a debugging function, and should normally be turned off. * * open_trace_file: Boolean field indicating whether the trace_file_name * field should be used to open a trace file for the cache. * * *** DEPRECATED *** Use H5Fstart/stop logging functions instead * * The trace file is a debuging feature that allow the capture of * top level metadata cache requests for purposes of debugging and/or * optimization. This field should normally be set to FALSE, as * trace file collection imposes considerable overhead. * * This field should only be set to TRUE when the trace_file_name * contains the full path of the desired trace file, and either * there is no open trace file on the cache, or the close_trace_file * field is also TRUE. * * close_trace_file: Boolean field indicating whether the current trace * file (if any) should be closed. * * *** DEPRECATED *** Use H5Fstart/stop logging functions instead * * See the above comments on the open_trace_file field. This field * should be set to FALSE unless there is an open trace file on the * cache that you wish to close. * * trace_file_name: Full path of the trace file to be opened if the * open_trace_file field is TRUE. * * *** DEPRECATED *** Use H5Fstart/stop logging functions instead * * In the parallel case, an ascii representation of the mpi rank of * the process will be appended to the file name to yield a unique * trace file name for each process. * * The length of the path must not exceed H5AC__MAX_TRACE_FILE_NAME_LEN * characters. * * evictions_enabled: Boolean field used to either report the current * evictions enabled status of the cache, or to set the cache's * evictions enabled status. * * In general, the metadata cache should always be allowed to * evict entries. However, in some cases it is advantageous to * disable evictions briefly, and thereby postpone metadata * writes. However, this must be done with care, as the cache * can grow quickly. If you do this, re-enable evictions as * soon as possible and monitor cache size. * * At present, evictions can only be disabled if automatic * cache resizing is also disabled (that is, ( incr_mode == * H5C_incr__off ) && ( decr_mode == H5C_decr__off )). There * is no logical reason why this should be so, but it simplifies * implementation and testing, and I can't think of any reason * why it would be desireable. If you can think of one, I'll * revisit the issue. * * set_initial_size: Boolean flag indicating whether the size of the * initial size of the cache is to be set to the value given in * the initial_size field. If set_initial_size is FALSE, the * initial_size field is ignored. * * initial_size: If enabled, this field contain the size the cache is * to be set to upon receipt of this structure. Needless to say, * initial_size must lie in the closed interval [min_size, max_size]. * * min_clean_fraction: double in the range 0 to 1 indicating the fraction * of the cache that is to be kept clean. This field is only used * in parallel mode. Typical values are 0.1 to 0.5. * * max_size: Maximum size to which the cache can be adjusted. The * supplied value must fall in the closed interval * [MIN_MAX_CACHE_SIZE, MAX_MAX_CACHE_SIZE]. Also, max_size must * be greater than or equal to min_size. * * min_size: Minimum size to which the cache can be adjusted. The * supplied value must fall in the closed interval * [H5C__MIN_MAX_CACHE_SIZE, H5C__MAX_MAX_CACHE_SIZE]. Also, min_size * must be less than or equal to max_size. * * epoch_length: Number of accesses on the cache over which to collect * hit rate stats before running the automatic cache resize code, * if it is enabled. * * At the end of an epoch, we discard prior hit rate data and start * collecting afresh. The epoch_length must lie in the closed * interval [H5C__MIN_AR_EPOCH_LENGTH, H5C__MAX_AR_EPOCH_LENGTH]. * * * Cache size increase control fields: * * incr_mode: Instance of the H5C_cache_incr_mode enumerated type whose * value indicates how we determine whether the cache size should be * increased. At present there are two possible values: * * H5C_incr__off: Don't attempt to increase the size of the cache * automatically. * * When this increment mode is selected, the remaining fields * in the cache size increase section ar ignored. * * H5C_incr__threshold: Attempt to increase the size of the cache * whenever the average hit rate over the last epoch drops * below the value supplied in the lower_hr_threshold * field. * * Note that this attempt will fail if the cache is already * at its maximum size, or if the cache is not already using * all available space. * * Note that you must set decr_mode to H5C_incr__off if you * disable metadata cache entry evictions. * * lower_hr_threshold: Lower hit rate threshold. If the increment mode * (incr_mode) is H5C_incr__threshold and the hit rate drops below the * value supplied in this field in an epoch, increment the cache size by * size_increment. Note that cache size may not be incremented above * max_size, and that the increment may be further restricted by the * max_increment field if it is enabled. * * When enabled, this field must contain a value in the range [0.0, 1.0]. * Depending on the incr_mode selected, it may also have to be less than * upper_hr_threshold. * * increment: Double containing the multiplier used to derive the new * cache size from the old if a cache size increment is triggered. * The increment must be greater than 1.0, and should not exceed 2.0. * * The new cache size is obtained my multiplying the current max cache * size by the increment, and then clamping to max_size and to stay * within the max_increment as necessary. * * apply_max_increment: Boolean flag indicating whether the max_increment * field should be used to limit the maximum cache size increment. * * max_increment: If enabled by the apply_max_increment field described * above, this field contains the maximum number of bytes by which the * cache size can be increased in a single re-size. * * flash_incr_mode: Instance of the H5C_cache_flash_incr_mode enumerated * type whose value indicates whether and by which algorithm we should * make flash increases in the size of the cache to accommodate insertion * of large entries and large increases in the size of a single entry. * * The addition of the flash increment mode was occasioned by performance * problems that appear when a local heap is increased to a size in excess * of the current cache size. While the existing re-size code dealt with * this eventually, performance was very bad for the remainder of the * epoch. * * At present, there are two possible values for the flash_incr_mode: * * H5C_flash_incr__off: Don't perform flash increases in the size of * the cache. * * H5C_flash_incr__add_space: Let x be either the size of a newly * newly inserted entry, or the number of bytes by which the * size of an existing entry has been increased. * * If * x > flash_threshold * current max cache size, * * increase the current maximum cache size by x * flash_multiple * less any free space in the cache, and star a new epoch. For * now at least, pay no attention to the maximum increment. * * In both of the above cases, the flash increment pays no attention to * the maximum increment (at least in this first incarnation), but DOES * stay within max_size. * * With a little thought, it should be obvious that the above flash * cache size increase algorithm is not sufficient for all circumstances * -- for example, suppose the user round robins through * (1/flash_threshold) +1 groups, adding one data set to each on each * pass. Then all will increase in size at about the same time, requiring * the max cache size to at least double to maintain acceptable * performance, however the above flash increment algorithm will not be * triggered. * * Hopefully, the add space algorithms detailed above will be sufficient * for the performance problems encountered to date. However, we should * expect to revisit the issue. * * flash_multiple: Double containing the multiple described above in the * H5C_flash_incr__add_space section of the discussion of the * flash_incr_mode section. This field is ignored unless flash_incr_mode * is H5C_flash_incr__add_space. * * flash_threshold: Double containing the factor by which current max cache * size is multiplied to obtain the size threshold for the add_space flash * increment algorithm. The field is ignored unless flash_incr_mode is * H5C_flash_incr__add_space. * * * Cache size decrease control fields: * * decr_mode: Instance of the H5C_cache_decr_mode enumerated type whose * value indicates how we determine whether the cache size should be * decreased. At present there are four possibilities. * * H5C_decr__off: Don't attempt to decrease the size of the cache * automatically. * * When this increment mode is selected, the remaining fields * in the cache size decrease section are ignored. * * H5C_decr__threshold: Attempt to decrease the size of the cache * whenever the average hit rate over the last epoch rises * above the value supplied in the upper_hr_threshold * field. * * H5C_decr__age_out: At the end of each epoch, search the cache for * entries that have not been accessed for at least the number * of epochs specified in the epochs_before_eviction field, and * evict these entries. Conceptually, the maximum cache size * is then decreased to match the new actual cache size. However, * this reduction may be modified by the min_size, the * max_decrement, and/or the empty_reserve. * * H5C_decr__age_out_with_threshold: Same as age_out, but we only * attempt to reduce the cache size when the hit rate observed * over the last epoch exceeds the value provided in the * upper_hr_threshold field. * * Note that you must set decr_mode to H5C_decr__off if you * disable metadata cache entry evictions. * * upper_hr_threshold: Upper hit rate threshold. The use of this field * varies according to the current decr_mode: * * H5C_decr__off or H5C_decr__age_out: The value of this field is * ignored. * * H5C_decr__threshold: If the hit rate exceeds this threshold in any * epoch, attempt to decrement the cache size by size_decrement. * * Note that cache size may not be decremented below min_size. * * Note also that if the upper_threshold is 1.0, the cache size * will never be reduced. * * H5C_decr__age_out_with_threshold: If the hit rate exceeds this * threshold in any epoch, attempt to reduce the cache size * by evicting entries that have not been accessed for more * than the specified number of epochs. * * decrement: This field is only used when the decr_mode is * H5C_decr__threshold. * * The field is a double containing the multiplier used to derive the * new cache size from the old if a cache size decrement is triggered. * The decrement must be in the range 0.0 (in which case the cache will * try to contract to its minimum size) to 1.0 (in which case the * cache will never shrink). * * apply_max_decrement: Boolean flag used to determine whether decrements * in cache size are to be limited by the max_decrement field. * * max_decrement: Maximum number of bytes by which the cache size can be * decreased in a single re-size. Note that decrements may also be * restricted by the min_size of the cache, and (in age out modes) by * the empty_reserve field. * * epochs_before_eviction: Integer field used in H5C_decr__age_out and * H5C_decr__age_out_with_threshold decrement modes. * * This field contains the number of epochs an entry must remain * unaccessed before it is evicted in an attempt to reduce the * cache size. If applicable, this field must lie in the range * [1, H5C__MAX_EPOCH_MARKERS]. * * apply_empty_reserve: Boolean field controlling whether the empty_reserve * field is to be used in computing the new cache size when the * decr_mode is H5C_decr__age_out or H5C_decr__age_out_with_threshold. * * empty_reserve: To avoid a constant racheting down of cache size by small * amounts in the H5C_decr__age_out and H5C_decr__age_out_with_threshold * modes, this field allows one to require that any cache size * reductions leave the specified fraction of unused space in the cache. * * The value of this field must be in the range [0.0, 1.0]. I would * expect typical values to be in the range of 0.01 to 0.1. * * * Parallel Configuration Fields: * * In PHDF5, all operations that modify metadata must be executed collectively. * * We used to think that this was enough to ensure consistency across the * metadata caches, but since we allow processes to read metadata individually, * the order of dirty entries in the LRU list can vary across processes, * which can result in inconsistencies between the caches. * * PHDF5 uses several strategies to prevent such inconsistencies in metadata, * all of which use the fact that the same stream of dirty metadata is seen * by all processes for purposes of synchronization. This is done by * having each process count the number of bytes of dirty metadata generated, * and then running a "sync point" whenever this count exceeds a user * specified threshold (see dirty_bytes_threshold below). * * The current metadata write strategy is indicated by the * metadata_write_strategy field. The possible values of this field, along * with the associated metadata write strategies are discussed below. * * dirty_bytes_threshold: Threshold of dirty byte creation used to * synchronize updates between caches. (See above for outline and * motivation.) * * This value MUST be consistent across all processes accessing the * file. This field is ignored unless HDF5 has been compiled for * parallel. * * metadata_write_strategy: Integer field containing a code indicating the * desired metadata write strategy. The valid values of this field * are enumerated and discussed below: * * * H5AC_METADATA_WRITE_STRATEGY__PROCESS_0_ONLY: * * When metadata_write_strategy is set to this value, only process * zero is allowed to write dirty metadata to disk. All other * processes must retain dirty metadata until they are informed at * a sync point that the dirty metadata in question has been written * to disk. * * When the sync point is reached (or when there is a user generated * flush), process zero flushes sufficient entries to bring it into * complience with its min clean size (or flushes all dirty entries in * the case of a user generated flush), broad casts the list of * entries just cleaned to all the other processes, and then exits * the sync point. * * Upon receipt of the broadcast, the other processes mark the indicated * entries as clean, and leave the sync point as well. * * * H5AC_METADATA_WRITE_STRATEGY__DISTRIBUTED: * * In the distributed metadata write strategy, process zero still makes * the decisions as to what entries should be flushed, but the actual * flushes are distributed across the processes in the computation to * the extent possible. * * In this strategy, when a sync point is triggered (either by dirty * metadata creation or manual flush), all processes enter a barrier. * * On the other side of the barrier, process 0 constructs an ordered * list of the entries to be flushed, and then broadcasts this list * to the caches in all the processes. * * All processes then scan the list of entries to be flushed, flushing * some, and marking the rest as clean. The algorithm for this purpose * ensures that each entry in the list is flushed exactly once, and * all are marked clean in each cache. * * Note that in the case of a flush of the cache, no message passing * is necessary, as all processes have the same list of dirty entries, * and all of these entries must be flushed. Thus in this case it is * sufficient for each process to sort its list of dirty entries after * leaving the initial barrier, and use this list as if it had been * received from process zero. * * To avoid possible messages from the past/future, all caches must * wait until all caches are done before leaving the sync point. * ****************************************************************************/ #define H5AC__CURR_CACHE_CONFIG_VERSION 1 #define H5AC__MAX_TRACE_FILE_NAME_LEN 1024 #define H5AC_METADATA_WRITE_STRATEGY__PROCESS_0_ONLY 0 #define H5AC_METADATA_WRITE_STRATEGY__DISTRIBUTED 1 typedef struct H5AC_cache_config_t { /* general configuration fields: */ int version; hbool_t rpt_fcn_enabled; hbool_t open_trace_file; hbool_t close_trace_file; char trace_file_name[H5AC__MAX_TRACE_FILE_NAME_LEN + 1]; hbool_t evictions_enabled; hbool_t set_initial_size; size_t initial_size; double min_clean_fraction; size_t max_size; size_t min_size; long int epoch_length; /* size increase control fields: */ enum H5C_cache_incr_mode incr_mode; double lower_hr_threshold; double increment; hbool_t apply_max_increment; size_t max_increment; enum H5C_cache_flash_incr_mode flash_incr_mode; double flash_multiple; double flash_threshold; /* size decrease control fields: */ enum H5C_cache_decr_mode decr_mode; double upper_hr_threshold; double decrement; hbool_t apply_max_decrement; size_t max_decrement; int epochs_before_eviction; hbool_t apply_empty_reserve; double empty_reserve; /* parallel configuration fields: */ size_t dirty_bytes_threshold; int metadata_write_strategy; } H5AC_cache_config_t; /**************************************************************************** * * structure H5AC_cache_image_config_t * * H5AC_cache_image_ctl_t is a public structure intended for use in public * APIs. At least in its initial incarnation, it is a copy of struct * H5C_cache_image_ctl_t. * * The fields of the structure are discussed individually below: * * version: Integer field containing the version number of this version * of the H5C_image_ctl_t structure. Any instance of * H5C_image_ctl_t passed to the cache must have a known * version number, or an error will be flagged. * * generate_image: Boolean flag indicating whether a cache image should * be created on file close. * * save_resize_status: Boolean flag indicating whether the cache image * should include the adaptive cache resize configuration and status. * Note that this field is ignored at present. * * entry_ageout: Integer field indicating the maximum number of * times a prefetched entry can appear in subsequent cache images. * This field exists to allow the user to avoid the buildup of * infrequently used entries in long sequences of cache images. * * The value of this field must lie in the range * H5AC__CACHE_IMAGE__ENTRY_AGEOUT__NONE (-1) to * H5AC__CACHE_IMAGE__ENTRY_AGEOUT__MAX (100). * * H5AC__CACHE_IMAGE__ENTRY_AGEOUT__NONE means that no limit * is imposed on number of times a prefeteched entry can appear * in subsequent cache images. * * A value of 0 prevents prefetched entries from being included * in cache images. * * Positive integers restrict prefetched entries to the specified * number of appearances. * * Note that the number of subsequent cache images that a prefetched * entry has appeared in is tracked in an 8 bit field. Thus, while * H5AC__CACHE_IMAGE__ENTRY_AGEOUT__MAX can be increased from its * current value, any value in excess of 255 will be the functional * equivalent of H5AC__CACHE_IMAGE__ENTRY_AGEOUT__NONE. * ****************************************************************************/ #define H5AC__CURR_CACHE_IMAGE_CONFIG_VERSION 1 #define H5AC__CACHE_IMAGE__ENTRY_AGEOUT__NONE -1 #define H5AC__CACHE_IMAGE__ENTRY_AGEOUT__MAX 100 typedef struct H5AC_cache_image_config_t { int version; hbool_t generate_image; hbool_t save_resize_status; int entry_ageout; } H5AC_cache_image_config_t; #ifdef __cplusplus } #endif #endif


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