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Fixed size of page_num variables. Added defines for when to do mmap()…
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… and whether to invoke copy-on-write
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@skaphan
skaphan committed Dec 12, 2009
1 parent 5be33a2 commit 11727ba
Showing 1 changed file with 59 additions and 16 deletions.
75 changes: 59 additions & 16 deletions stm.c
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Expand Up @@ -37,6 +37,7 @@
#include "atomic-compat.h"
#include "stm.h"

#undef PER_PAGE_MMAPS

#define MAX_ACTIVE_TRANSACTIONS 100

Expand Down Expand Up @@ -397,7 +398,7 @@ shared_segment *stm_open_shared_segment(char *filename, size_t segment_size, voi
status = mmap(requested_va, seg->shared_seg_size, seg->default_prot_flags, mmap_flags, seg->fd, (off_t)0);

if (status != (void*)-1) {
seg->shared_base_va = status;
seg->shared_base_va = status;
// fprintf(stderr, "shared base va = %x\n", status);
} else {
if (stm_verbose & 1)
Expand All @@ -407,6 +408,7 @@ shared_segment *stm_open_shared_segment(char *filename, size_t segment_size, voi
return NULL;
}


status = mmap(0, seg->transaction_data_size, PROT_READ|PROT_WRITE, MAP_SHARED, seg->metadata_fd, (off_t)0);

if (status != (void*)-1) {
Expand Down Expand Up @@ -472,7 +474,7 @@ static void free_snapshot_list(shared_segment *seg) {

static void abort_transaction_on_segment(shared_segment *seg) {
snapshot_list_element *sl;
int page_num;
size_t page_num;
page_table_element *page_table_elt;
void *status;

Expand All @@ -494,7 +496,7 @@ static void abort_transaction_on_segment(shared_segment *seg) {

if (stm_verbose & 4) {
int dirty = memcmp(sl->original_page_va, sl->original_page_snapshot, seg->page_size);
fprintf(stderr, " %s%x", dirty? "*":"", page_num);
fprintf(stderr, " %s%lx", dirty? "*":"", page_num);
}

if (page_table_elt->current_transaction == seg->transaction_id) {
Expand All @@ -506,6 +508,19 @@ static void abort_transaction_on_segment(shared_segment *seg) {
page_table_elt->current_transaction = 0;
}


#ifdef PER_PAGE_MMAPS
if (seg->default_prot_flags == PROT_NONE) {
status = (void*)(long)mprotect(sl->original_page_va, seg->page_size, PROT_NONE);
} else
{
status = mmap(sl->original_page_va, seg->page_size, seg->default_prot_flags, MAP_FIXED|MAP_SHARED, seg->fd,
(off_t)(sl->original_page_va - seg->shared_base_va));
}
if (status == (void*)-1)
perror("abort_transaction_on_segment: mmap error");
#endif

}

if (stm_verbose & 4)
Expand All @@ -515,10 +530,17 @@ static void abort_transaction_on_segment(shared_segment *seg) {

// reprotect *all* pages with the default inter-transaction protection.

status = mmap(seg->shared_base_va, seg->shared_seg_size, seg->default_prot_flags, MAP_FIXED|MAP_SHARED, seg->fd,
(off_t)0);
#ifndef PER_PAGE_MMAPS
if (seg->default_prot_flags == PROT_NONE) {
status = (void*)(long)mprotect(seg->shared_base_va, seg->shared_seg_size, PROT_NONE);
} else
{
status = mmap(seg->shared_base_va, seg->shared_seg_size, seg->default_prot_flags, MAP_FIXED|MAP_SHARED, seg->fd,
(off_t)0);
}
if (status == (void*)-1)
perror("abort_transaction_on_segment: mmap error");
#endif

seg->transaction_id = 0;

Expand Down Expand Up @@ -705,7 +727,7 @@ static void signal_handler(int sig, siginfo_t *si, void *foo) {
shared_segment *seg;
page_table_element *page_table_elt;
transaction_id_t completed_transaction;
int page_num;
size_t page_num;

struct sigaction sa;

Expand Down Expand Up @@ -753,14 +775,14 @@ static void signal_handler(int sig, siginfo_t *si, void *foo) {
if (seg->transaction_id != page_table_elt->current_transaction) {

if (stm_verbose & 2)
fprintf(stderr, "Transaction %d owns page %x while transaction %d is snapshotting it.\n",
fprintf(stderr, "Transaction %d owns page %lx while transaction %d is snapshotting it.\n",
page_table_elt->current_transaction, page_num, seg->transaction_id);
collision_histo[0]++;
transaction_error_exit(STM_COLLISION_ERROR, 1);
return;
} else {
if (stm_verbose & 1)
fprintf(stderr, "Transaction %d already owns page %x\n",
fprintf(stderr, "Transaction %d already owns page %lx\n",
page_table_elt->current_transaction, page_num);
transaction_error_exit(STM_OWNERSHIP_ERROR, -1);
}
Expand All @@ -784,7 +806,7 @@ static void signal_handler(int sig, siginfo_t *si, void *foo) {
if ((int32_t)completed_transaction - (int32_t)seg->transaction_id > 0) {

if (stm_verbose & 2)
fprintf(stderr, "On page %x, current transaction %d is before page's completed transaction %d\n",
fprintf(stderr, "On page %lx, current transaction %d is before page's completed transaction %d\n",
page_num, seg->transaction_id, completed_transaction);

collision_histo[1]++;
Expand All @@ -794,7 +816,7 @@ static void signal_handler(int sig, siginfo_t *si, void *foo) {

if (find_prior_active_transaction(seg, completed_transaction)) {
if (stm_verbose & 2)
fprintf(stderr, "On page %x, completed transaction %d was active when transaction %d started\n",
fprintf(stderr, "On page %lx, completed transaction %d was active when transaction %d started\n",
page_num, completed_transaction, seg->transaction_id);
collision_histo[2]++;
transaction_error_exit(STM_COLLISION_ERROR, 1);
Expand All @@ -804,6 +826,7 @@ static void signal_handler(int sig, siginfo_t *si, void *foo) {

// Change from shared to private mapping, and make the page readable and writable.
//

status = mmap(page_base, seg->page_size, PROT_READ|PROT_WRITE, MAP_FIXED|MAP_PRIVATE, seg->fd,
(off_t)(page_base - seg->shared_base_va));

Expand All @@ -815,11 +838,13 @@ static void signal_handler(int sig, siginfo_t *si, void *foo) {

}

#ifdef PRIVATE_MAPPING_NOT_PRIVATE
// Some systems evidently allow changes by other processes to be reflected in private mappings.
// To prevent that (hopefully!) we modify the page (without really changing anything) to
// invoke the "copy-on-write" semantics and really make a private copy
//
*(volatile int*)page_base = defeat_optimizer((volatile int*)page_base);
#endif

if (insert_into_snapshot_list(seg, page_base, completed_transaction) != 0) {
transaction_error_exit(0, -1);
Expand All @@ -831,15 +856,15 @@ static void signal_handler(int sig, siginfo_t *si, void *foo) {
if (seg->transaction_id != page_table_elt->current_transaction) {

if (stm_verbose & 2)
fprintf(stderr, "Transaction %d owns page %x while transaction %d is snapshotting it. [2]\n",
fprintf(stderr, "Transaction %d owns page %lx while transaction %d is snapshotting it. [2]\n",
page_table_elt->current_transaction, page_num, seg->transaction_id);
collision_histo[3]++;
transaction_error_exit(STM_COLLISION_ERROR, 1);
return;
} else {
#ifdef OPTIMISTIC_LOCKING
if (stm_verbose & 1)
fprintf(stderr, "Transaction %d already owns page %x [2]\n",
fprintf(stderr, "Transaction %d already owns page %lx [2]\n",
page_table_elt->current_transaction, page_num);
transaction_error_exit(STM_OWNERSHIP_ERROR, -1);
#endif
Expand All @@ -848,7 +873,7 @@ static void signal_handler(int sig, siginfo_t *si, void *foo) {

if (completed_transaction != page_table_elt->completed_transaction) {
if (stm_verbose & 2) {
fprintf(stderr, "Transaction %d snuck in on transaction %d on page %x during snapshot\n",
fprintf(stderr, "Transaction %d snuck in on transaction %d on page %lx during snapshot\n",
page_table_elt->completed_transaction, completed_transaction, page_num);
}
collision_histo[4]++;
Expand Down Expand Up @@ -952,7 +977,7 @@ int _stm_start_transaction(char *trans_name) {
//
static int lock_segment_pages(shared_segment *seg) {
snapshot_list_element *sl;
unsigned long page_num;
size_t page_num;
page_table_element *page_table_elt;

if (seg->transaction_id == 0) {
Expand Down Expand Up @@ -1049,14 +1074,16 @@ static int write_locked_segment_pages(shared_segment *seg) {

snapshot_list_element *sl;
void *status;
unsigned long page_num;
size_t page_num;
int result = 0;

page_table_element *page_table_elt;


// Re-map shared.


#ifndef PER_PAGE_MMAPS
status = mmap(seg->shared_base_va, seg->shared_seg_size, PROT_READ|PROT_WRITE, MAP_FIXED|MAP_SHARED, seg->fd,
(off_t)0);
if (status == (void*)-1) {
Expand All @@ -1065,6 +1092,7 @@ static int write_locked_segment_pages(shared_segment *seg) {
set_stm_errno(STM_MMAP_ERROR);
return -1;
}
#endif

if (stm_verbose & 4)
fprintf(stderr, "Transaction %d [", seg->transaction_id);
Expand All @@ -1081,12 +1109,26 @@ static int write_locked_segment_pages(shared_segment *seg) {
if (stm_verbose & 4)
fprintf(stderr, " %lx", page_num);

#ifdef PER_PAGE_MMAPS
status = mmap(sl->original_page_va, seg->page_size, PROT_READ|PROT_WRITE, MAP_FIXED|MAP_SHARED, seg->fd,
(off_t)(sl->original_page_va - seg->shared_base_va));
if (status == (void*)-1) {
if (stm_verbose & 1)
perror("write_locked_pages: mmap error");
set_stm_errno(STM_MMAP_ERROR);
return -1;
}
#endif
page_table_elt->completed_transaction = seg->transaction_id;

// copy the temporarily saved, modified pages back into the right places
//
memcpy(sl->original_page_va, sl->original_page_snapshot, seg->page_size);

#ifdef PER_PAGE_MMAPS
if (seg->default_prot_flags != (PROT_READ|PROT_WRITE))
mprotect(sl->original_page_va, seg->page_size, seg->default_prot_flags);
#endif
}

if (page_table_elt->current_transaction == seg->transaction_id) {
Expand All @@ -1097,16 +1139,17 @@ static int write_locked_segment_pages(shared_segment *seg) {

page_table_elt->current_transaction = 0;
}

}

if (stm_verbose & 4)
fprintf(stderr, " ]\n");

// re-protect the segment to be whatever it is supposed to be between transactions

#ifndef PER_PAGE_MMAPS
if (seg->default_prot_flags != (PROT_READ|PROT_WRITE))
mprotect(seg->shared_base_va, seg->shared_seg_size, seg->default_prot_flags);
#endif

free_snapshot_list(seg);

Expand Down

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