Index: src/os_unix.c ================================================================== --- src/os_unix.c +++ src/os_unix.c @@ -4103,10 +4103,37 @@ #endif return rc; } +/* +** Return the system page size. +*/ +static int unixGetPagesize(void){ +#if defined(_BSD_SOURCE) + return getpagesize(); +#else + return (int)sysconf(_SC_PAGESIZE); +#endif +} + +/* +** Return the minimum number of 32KB shm regions that should be mapped at +** a time, assuming that each mapping must be an integer multiple of the +** current system page-size. +** +** Usually, this is 1. The exception seems to be systems that are configured +** to use 64KB pages - in this case each mapping must cover at least two +** shm regions. +*/ +static int unixShmRegionPerMap(void){ + int shmsz = 32*1024; /* SHM region size */ + int pgsz = unixGetPagesize(); /* System page size */ + assert( ((pgsz-1)&pgsz)==0 ); /* Page size must be a power of 2 */ + if( pgszpInode->pShmNode; assert( unixMutexHeld() ); if( p && p->nRef==0 ){ + int nShmPerMap = unixShmRegionPerMap(); int i; assert( p->pInode==pFd->pInode ); sqlite3_mutex_free(p->mutex); - for(i=0; inRegion; i++){ + for(i=0; inRegion; i+=nShmPerMap){ if( p->h>=0 ){ osMunmap(p->apRegion[i], p->szRegion); }else{ sqlite3_free(p->apRegion[i]); } @@ -4324,10 +4352,12 @@ ){ unixFile *pDbFd = (unixFile*)fd; unixShm *p; unixShmNode *pShmNode; int rc = SQLITE_OK; + int nShmPerMap = unixShmRegionPerMap(); + int nReqRegion; /* If the shared-memory file has not yet been opened, open it now. */ if( pDbFd->pShm==0 ){ rc = unixOpenSharedMemory(pDbFd); if( rc!=SQLITE_OK ) return rc; @@ -4339,13 +4369,16 @@ assert( szRegion==pShmNode->szRegion || pShmNode->nRegion==0 ); assert( pShmNode->pInode==pDbFd->pInode ); assert( pShmNode->h>=0 || pDbFd->pInode->bProcessLock==1 ); assert( pShmNode->h<0 || pDbFd->pInode->bProcessLock==0 ); - if( pShmNode->nRegion<=iRegion ){ + /* Minimum number of regions required to be mapped. */ + nReqRegion = ((iRegion+nShmPerMap) / nShmPerMap) * nShmPerMap; + + if( pShmNode->nRegionszRegion = szRegion; if( pShmNode->h>=0 ){ @@ -4390,21 +4423,23 @@ } } /* Map the requested memory region into this processes address space. */ apNew = (char **)sqlite3_realloc( - pShmNode->apRegion, (iRegion+1)*sizeof(char *) + pShmNode->apRegion, nReqRegion*sizeof(char *) ); if( !apNew ){ rc = SQLITE_IOERR_NOMEM; goto shmpage_out; } pShmNode->apRegion = apNew; - while(pShmNode->nRegion<=iRegion){ + while( pShmNode->nRegionh>=0 ){ - pMem = osMmap(0, szRegion, + pMem = osMmap(0, nMap, pShmNode->isReadonly ? PROT_READ : PROT_READ|PROT_WRITE, MAP_SHARED, pShmNode->h, szRegion*(i64)pShmNode->nRegion ); if( pMem==MAP_FAILED ){ rc = unixLogError(SQLITE_IOERR_SHMMAP, "mmap", pShmNode->zFilename); @@ -4416,12 +4451,15 @@ rc = SQLITE_NOMEM; goto shmpage_out; } memset(pMem, 0, szRegion); } - pShmNode->apRegion[pShmNode->nRegion] = pMem; - pShmNode->nRegion++; + + for(i=0; iapRegion[pShmNode->nRegion+i] = &((char*)pMem)[szRegion*i]; + } + pShmNode->nRegion += nShmPerMap; } } shmpage_out: if( pShmNode->nRegion>iRegion ){ @@ -4631,23 +4669,10 @@ pFd->mmapSize = 0; pFd->mmapSizeActual = 0; } } -/* -** Return the system page size. -*/ -static int unixGetPagesize(void){ -#if HAVE_MREMAP - return 512; -#elif defined(_BSD_SOURCE) - return getpagesize(); -#else - return (int)sysconf(_SC_PAGESIZE); -#endif -} - /* ** Attempt to set the size of the memory mapping maintained by file ** descriptor pFd to nNew bytes. Any existing mapping is discarded. ** ** If successful, this function sets the following variables: @@ -4680,12 +4705,16 @@ assert( MAP_FAILED!=0 ); if( (pFd->ctrlFlags & UNIXFILE_RDONLY)==0 ) flags |= PROT_WRITE; if( pOrig ){ +#if HAVE_MREMAP + i64 nReuse = pFd->mmapSize; +#else const int szSyspage = unixGetPagesize(); i64 nReuse = (pFd->mmapSize & ~(szSyspage-1)); +#endif u8 *pReq = &pOrig[nReuse]; /* Unmap any pages of the existing mapping that cannot be reused. */ if( nReuse!=nOrig ){ osMunmap(pReq, nOrig-nReuse);