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Diffstat (limited to 'src/H5ACpkg.h')
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diff --git a/src/H5ACpkg.h b/src/H5ACpkg.h new file mode 100644 index 0000000..903eca3 --- /dev/null +++ b/src/H5ACpkg.h @@ -0,0 +1,315 @@ +/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * + * 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 files COPYING and Copyright.html. COPYING can be found at the root * + * of the source code distribution tree; Copyright.html can be found at the * + * root level of an installed copy of the electronic HDF5 document set and * + * is linked from the top-level documents page. It can also be found at * + * http://hdf.ncsa.uiuc.edu/HDF5/doc/Copyright.html. If you do not have * + * access to either file, you may request a copy from hdfhelp@ncsa.uiuc.edu. * + * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */ + +/* + * Programmer: John Mainzer -- 4/19/06 + * + * Purpose: This file contains declarations which are normally visible + * only within the H5AC package (just H5AC.c at present). + * + * Source files outside the H5AC package should include + * H5ACprivate.h instead. + * + * The one exception to this rule is testpar/t_cache.c. The + * test code is easier to write if it can look at H5AC_aux_t. + * Indeed, this is the main reason why this file was created. + */ + +#ifndef H5AC_PACKAGE +#error "Do not include this file outside the H5AC package!" +#endif + +#ifndef _H5ACpkg_H +#define _H5ACpkg_H + +#define H5C_PACKAGE /*suppress error about including H5Cpkg */ + +/* Get package's private header */ +#include "H5Cprivate.h" + + +/* Get needed headers */ +#include "H5Cpkg.h" /* Cache */ +#include "H5SLprivate.h" /* Skip lists */ + +#ifdef H5_HAVE_PARALLEL +#include <mpi.h> +#endif /* H5_HAVE_PARALLEL */ + + +#define H5AC_DEBUG_DIRTY_BYTES_CREATION 0 + +/*------------------------------------------------------------------------- + * It is a bit difficult to set ranges of allowable values on the + * dirty_bytes_threshold field of H5AC_aux_t. The following are + * probably broader than they should be. + *------------------------------------------------------------------------- + */ + +#define H5AC__MIN_DIRTY_BYTES_THRESHOLD (int32_t) \ + (H5C__MIN_MAX_CACHE_SIZE / 2) +#define H5AC__DEFAULT_DIRTY_BYTES_THRESHOLD (256 * 1024) +#define H5AC__MAX_DIRTY_BYTES_THRESHOLD (int32_t) \ + (H5C__MAX_MAX_CACHE_SIZE / 4) + +/**************************************************************************** + * + * structure H5AC_aux_t + * + * While H5AC has become a wrapper for the cache implemented in H5C.c, there + * are some features of the metadata cache that are specific to it, and which + * therefore do not belong in the more generic H5C cache code. + * + * In particular, there is the matter of synchronizing writes from the + * metadata cache to disk in the PHDF5 case. + * + * Prior to this update, the presumption was that all metadata caches would + * write the same data at the same time since all operations modifying + * metadata must be performed collectively. Given this assumption, it was + * safe to allow only the writes from process 0 to actually make it to disk, + * while metadata writes from all other processes were discarded. + * + * Unfortunately, this presumption is in error as operations that read + * metadata need not be collective, but can change the location of dirty + * entries in the metadata cache LRU lists. This can result in the same + * metadata write operation triggering writes from the metadata caches on + * some processes, but not all (causing a hang), or in different sets of + * entries being written from different caches (potentially resulting in + * metadata corruption in the file). + * + * To deal with this issue, I decided to apply a paradigm shift to the way + * metadata is written to disk. + * + * With this set of changes, only the metadata cache on process 0 is able + * to write metadata to disk, although metadata caches on all other + * processes can read metadata from disk as before. + * + * To keep all the other caches from getting plugged up with dirty metadata, + * process 0 periodically broadcasts a list of entries that it has flushed + * since that last notice, and which are currently clean. The other caches + * mark these entries as clean as well, which allows them to evict the + * entries as needed. + * + * One obvious problem in this approach is synchronizing the broadcasts + * and receptions, as different caches may see different amounts of + * activity. + * + * The current solution is for the caches to track the number of bytes + * of newly generated dirty metadata, and to broadcast and receive + * whenever this value exceeds some user specified threshold. + * + * Maintaining this count is easy for all processes not on process 0 -- + * all that is necessary is to add the size of the entry to the total + * whenever there is an insertion, a rename of a previously clean entry, + * or whever a previously clean entry is marked dirty in an unprotect. + * + * On process 0, we have to be careful not to count dirty bytes twice. + * If an entry is marked dirty, flushed, and marked dirty again, all + * within a single reporting period, it only th first marking should + * be added to the dirty bytes generated tally, as that is all that + * the other processes will see. + * + * At present, this structure exists to maintain the fields needed to + * implement the above scheme, and thus is only used in the parallel + * case. However, other uses may arise in the future. + * + * Instance of this structure are associated with metadata caches via + * the aux_ptr field of H5C_t (see H5Cpkg.h). The H5AC code is + * responsible for allocating, maintaining, and discarding instances + * of H5AC_aux_t. + * + * The remainder of this header comments documents the individual fields + * of the structure. + * + * JRM - 6/27/05 + * + * magic: Unsigned 32 bit integer always set to + * H5AC__H5AC_AUX_T_MAGIC. This field is used to validate + * pointers to instances of H5AC_aux_t. + * + * mpi_comm: MPI communicator associated with the file for which the + * cache has been created. + * + * mpi_rank: MPI rank of this process within mpi_comm. + * + * mpi_size: Number of processes in mpi_comm. + * + * write_permitted: Boolean flag used to control whether the cache + * is permitted to write to file. + * + * dirty_bytes_threshold: Integer field containing the dirty bytes + * generation threashold. Whenever dirty byte creation + * exceeds this value, the metadata cache on process 0 + * broadcasts a list of the entries it has flushed since + * the last broadcast (or since the beginning of execution) + * and which are currently clean (if they are still in the + * cache) + * + * Similarly, metadata caches on processes other than process + * 0 will attempt to receive a list of clean entries whenever + * the threshold is exceeded. + * + * dirty_bytes: Integer field containing the number of bytes of dirty + * metadata generated since the beginning of the computation, + * or (more typically) since the last clean entries list + * broadcast. This field is reset to zero after each such + * broadcast. + * + * dirty_bytes_propagations: This field only exists when the + * H5AC_DEBUG_DIRTY_BYTES_CREATION #define is TRUE. + * + * It is used to track the number of times the cleaned list + * has been propagated from process 0 to the other + * processes. + * + * unprotect_dirty_bytes: This field only exists when the + * H5AC_DEBUG_DIRTY_BYTES_CREATION #define is TRUE. + * + * It is used to track the number of dirty bytes created + * via unprotect operations since the last time the cleaned + * list was propagated. + * + * unprotect_dirty_bytes_updates: This field only exists when the + * H5AC_DEBUG_DIRTY_BYTES_CREATION #define is TRUE. + * + * It is used to track the number of times dirty bytes have + * been created via unprotect operations since the last time + * the cleaned list was propagated. + * + * insert_dirty_bytes: This field only exists when the + * H5AC_DEBUG_DIRTY_BYTES_CREATION #define is TRUE. + * + * It is used to track the number of dirty bytes created + * via insert operations since the last time the cleaned + * list was propagated. + * + * insert_dirty_bytes_updates: This field only exists when the + * H5AC_DEBUG_DIRTY_BYTES_CREATION #define is TRUE. + * + * It is used to track the number of times dirty bytes have + * been created via insert operations since the last time + * the cleaned list was propagated. + * + * rename_dirty_bytes: This field only exists when the + * H5AC_DEBUG_DIRTY_BYTES_CREATION #define is TRUE. + * + * It is used to track the number of dirty bytes created + * via rename operations since the last time the cleaned + * list was propagated. + * + * rename_dirty_bytes_updates: This field only exists when the + * H5AC_DEBUG_DIRTY_BYTES_CREATION #define is TRUE. + * + * It is used to track the number of times dirty bytes have + * been created via rename operations since the last time + * the cleaned list was propagated. + * + * d_slist_ptr: Pointer to an instance of H5SL_t used to maintain a list + * of entries that have been dirtied since the last time they + * were listed in a clean entries broadcast. This list is + * only maintained by the metadata cache on process 0 -- it + * it used to maintain a view of the dirty entries as seen + * by the other caches, so as to keep the dirty bytes count + * in synchronization with them. + * + * Thus on process 0, the dirty_bytes count is incremented + * only if either + * + * 1) an entry is inserted in the metadata cache, or + * + * 2) a previously clean entry is renamed, and it does not + * already appear in the dirty entry list, or + * + * 3) a previously clean entry is unprotected with the + * dirtied flag set and the entry does not already appear + * in the dirty entry list. + * + * Entries are added to the dirty entry list whever they cause + * the dirty bytes count to be increased. They are removed + * when they appear in a clean entries broadcast. Note that + * renames must be reflected in the dirty entry list. + * + * To reitterate, this field is only used on process 0 -- it + * should be NULL on all other processes. + * + * d_slist_len: Integer field containing the number of entries in the + * dirty entry list. This field should always contain the + * value 0 on all processes other than process 0. It exists + * primarily for sanity checking. + * + * c_slist_ptr: Pointer to an instance of H5SL_t used to maintain a list + * of entries that were dirty, have been flushed + * to disk since the last clean entries broadcast, and are + * still clean. Since only process 0 can write to disk, this + * list only exists on process 0. + * + * In essence, this slist is used to assemble the contents of + * the next clean entries broadcast. The list emptied after + * each broadcast. + * + * c_slist_len: Integer field containing the number of entries in the clean + * entries list (*c_slist_ptr). This field should always + * contain the value 0 on all processes other than process 0. + * It exists primarily for sanity checking. + * + ****************************************************************************/ + +#ifdef H5_HAVE_PARALLEL + +#define H5AC__H5AC_AUX_T_MAGIC (unsigned)0x00D0A01 + +typedef struct H5AC_aux_t +{ + uint32_t magic; + + MPI_Comm mpi_comm; + + int mpi_rank; + + int mpi_size; + + hbool_t write_permitted; + + int32_t dirty_bytes_threshold; + + int32_t dirty_bytes; + +#if H5AC_DEBUG_DIRTY_BYTES_CREATION + + int32_t dirty_bytes_propagations; + + int32_t unprotect_dirty_bytes; + int32_t unprotect_dirty_bytes_updates; + + int32_t insert_dirty_bytes; + int32_t insert_dirty_bytes_updates; + + int32_t rename_dirty_bytes; + int32_t rename_dirty_bytes_updates; + +#endif /* H5AC_DEBUG_DIRTY_BYTES_CREATION */ + + H5SL_t * d_slist_ptr; + + int32_t d_slist_len; + + H5SL_t * c_slist_ptr; + + int32_t c_slist_len; + +} H5AC_aux_t; /* struct H5AC_aux_t */ + +#endif /* H5_HAVE_PARALLEL */ + +#endif /* _H5Cpkg_H */ |