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slightly increases the performance. It also moderately improves the nr of cases where helgrind can provide the stack trace of the old access (when using the same amount of memory for the OldRef entries). The patch also provides a new helgrind monitor command to show the recorded accesses for an address+len, and adds an optional argument lock_address to the monitor command 'info locks', to show the info about just this lock. Currently, oldref are maintained in a sparse WA, that points to N entries, as specified by --conflict-cache-size=N. For each entry (associated to an address), we have the last 5 accesses. Old entries are recycled in an exact LRU order. But inside an entry, we could have a recent access, and 4 very old accesses that are kept 'alive' by a single thread accessing repetitively the address shared with the 4 other old entries. The attached patch replaces the sparse WA that maintains the OldREf by an hash table. Each OldRef now also only maintains one single access for an address. As an OldRef now maintains only one access, all the entries are now strictly in LRU mode. Memory used for OldRef ----------------------- For the trunk, an OldRef has a size of 72 bytes (on 32 bits archs) maintaining up to 5 accesses to the same address. On 64 bits arch, an OldRef is 104 bytes. With the patch, an OldRef has a size of 32 bytes (on 32 bits archs) or 56 bytes (on 64 bits archs). So, for one single access, the new code needs (on 32 bits) 32 bytes, while the trunk needs only 14.4 bytes. However, that is the worst case, assuming that the 5 entries in the accs array are all used. Looking on 2 big apps (one of them being firefox), we see that we have very few OldRef entries that have the 5 entries occupied. On a firefox startup, of the 5x1,000,000 accesses, we only have 1,406,939 accesses that are used. So, in average, the trunk uses in reality around 52 bytes per access. The default value for --conflict-cache-size has been doubled to 2000000. This ensures that the memory used for the OldRef is more or less the same as the trunk (104Mb for OldRef entries). Memory used for sparseWA versus hashtable ----------------------------------------- Looking on 2 big apps (one of them being firefox), we see that there are big variations on the size of the WA : it can go in a few seconds from 10MB to 250MB, or can decrease back to 10 MB. This all depends where the last N accesses were done: if well localised, the WA will be small. If the last N accesses were distributed over a big address space, then the WA will be big: the last level of WA (the biggest memory consumer) uses slightly more than 1KB (2KB on 64 bits) for each '256 bytes' memory zone where there is an oldref. So, in the worst case, on 32 bits, we need > 1_000_000_000 sparseWA memory to keep 1_000_000 OldRef. The hash table has between 1 to 2 Word overhead per OldRef (as the chain array is +- doubled each time the hash table is full). So, unless the OldRef are extremely localised, the overhead of the hash table will be significantly less. With the patch, the core arena total alloc is: 5299535/1201448632 totalloc-blocks/bytes The trunk is 6693111/3959050280 totalloc-blocks/bytes (so, around 1.20Gb versus 3.95Gb). This big difference is due to the fact that the sparseWA repetitively allocates then frees Level0 or LevelN when OldRef in the region covered by the Level0/N have all been recycled. In terms of CPU --------------- With the patch, on amd64, a firefox startup seems slightly faster (around 1%). The peak memory mmaped/used decreases by 200Mb. For a libreoffice test, the memory decreases by 230Mb. CPU also decreases slightly (1%). In terms of correctness: ----------------------- The trunk could potentially show not the most recent access to the memory of a race : the first OldRef entry matching the raced upon address was used, while we could have a more recent access in a following OldRef entry. In other words, the trunk only guaranteed to find the most recent access in an OldRef, but not between the several OldRef that could cover the raced upon address. So, assuming it is important to show the most recent access, this patch ensures we really show the most recent access, even in presence of overlapping accesses. git-svn-id: svn://svn.valgrind.org/valgrind/trunk@15289
95 lines
4.2 KiB
C
95 lines
4.2 KiB
C
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/*--------------------------------------------------------------------*/
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/*--- Error management for Helgrind. ---*/
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/*--- hg_errors.h ---*/
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/*--------------------------------------------------------------------*/
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/*
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This file is part of Helgrind, a Valgrind tool for detecting errors
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in threaded programs.
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Copyright (C) 2007-2013 OpenWorks Ltd
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info@open-works.co.uk
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This program is free software; you can redistribute it and/or
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modify it under the terms of the GNU General Public License as
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published by the Free Software Foundation; either version 2 of the
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License, or (at your option) any later version.
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This program is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
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02111-1307, USA.
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The GNU General Public License is contained in the file COPYING.
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*/
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#ifndef __HG_ERRORS_H
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#define __HG_ERRORS_H
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/* The standard bundle of error management functions that we are
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required to present to the core/tool interface at startup. */
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Bool HG_(eq_Error) ( VgRes not_used, const Error* e1, const Error* e2 );
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void HG_(before_pp_Error) ( const Error* err );
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void HG_(pp_Error) ( const Error* err );
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UInt HG_(update_extra) ( const Error* err );
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Bool HG_(recognised_suppression) ( const HChar* name, Supp *su );
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Bool HG_(read_extra_suppression_info) ( Int fd, HChar** bufpp, SizeT* nBufp,
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Int* lineno, Supp* su );
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Bool HG_(error_matches_suppression) ( const Error* err, const Supp* su );
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const HChar* HG_(get_error_name) ( const Error* err );
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SizeT HG_(get_extra_suppression_info) ( const Error* err,
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/*OUT*/HChar* buf, Int nBuf );
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SizeT HG_(print_extra_suppression_use) ( const Supp* su,
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/*OUT*/HChar* buf, Int nBuf );
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void HG_(update_extra_suppression_use) ( const Error* err, const Supp* su );
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/* Functions for recording various kinds of errors. */
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void HG_(record_error_Race) ( Thread* thr,
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Addr data_addr, Int szB, Bool isWrite,
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Thread* h1_confthr,
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ExeContext* h1_ct_segstart,
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ExeContext* h1_ct_mbsegend );
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void HG_(record_error_UnlockUnlocked) ( Thread*, Lock* );
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void HG_(record_error_UnlockForeign) ( Thread*, Thread*, Lock* );
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void HG_(record_error_UnlockBogus) ( Thread*, Addr );
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void HG_(record_error_PthAPIerror) ( Thread*, const HChar*, Word,
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const HChar* );
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/* Function for printing the details about an access */
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void HG_(print_access) (StackTrace ips, UInt n_ips,
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Thr* thr_a,
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Addr ga,
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SizeT SzB,
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Bool isW,
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WordSetID locksHeldW );
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/* see the implementation for meaning of these params */
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void HG_(record_error_LockOrder) ( Thread*, Lock*, Lock*,
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ExeContext*, ExeContext*,
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ExeContext* );
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void HG_(record_error_Misc_w_aux) ( Thread*, const HChar* errstr,
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const HChar* auxstr,
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ExeContext* auxctx );
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void HG_(record_error_Misc) ( Thread* thr, const HChar* errstr );
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/* Statistics pertaining to error management. */
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extern ULong HG_(stats__LockN_to_P_queries);
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extern ULong HG_(stats__LockN_to_P_get_map_size) ( void );
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extern ULong HG_(stats__string_table_queries);
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extern ULong HG_(stats__string_table_get_map_size) ( void );
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#endif /* ! __HG_ERRORS_H */
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/*--------------------------------------------------------------------*/
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/*--- end hg_errors.h ---*/
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/*--------------------------------------------------------------------*/
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