sihangliu / pmtest Goto Github PK

Hello,

I'm wondering whether or not PMTest's transactions are concurrent-safe. As in, does it require external synchronization to access persistent memory? Is it possible to implement persistent non-blocking concurrent algorithms using these transactions?

Hello developers,

I was wondering whether or not the instrumentation PMTest_* function (i.e. PMTest_assign, PMTest_flush, PMTest_fence), must be placed manually, or if there is some kind of compiler plugin that I'm missing. Assume I am not using any transactions and am doing it the old-fashioned manually clflush; sfence (or clwb/clflushopt) approach to persistence. I was looking to modify this...

https://github.com/pmem/pmdk/blob/0206f00217755e9b638fae01188e0408fb1e31e6/src/examples/pmreorder/pmreorder_list.c#L140-L153

Since new->next and new->value are meant to persist before the write to root->head, but this example deliberately violates this by persisting root->head before new->value. How would I catch this in PMTest? I got...

void list_insert_inconsistent(struct list_root *root, node_id node, int value)
{
        struct list_node *new = NODE_PTR(root, node);
        PMTest_isPersistedBefore(&new->value, sizeof(new->value),  &root->head, sizeof(root->head));
        PMTest_isPersistedBefore(&new->next, sizeof(new->next), &root->head, sizeof(root->head));

        new->next = root->head;
        PMTest_assign(&new->next, sizeof(new->next));
        PMTest_flush(&new->next, sizeof(new->next));
        PMTest_fence();

        root->head = node;
        PMTest_assign(&root->head, sizeof(root->head));
        PMTest_flush(&root->head, sizeof(root->head));
        PMTest_fence();

        new->value = value;
        PMTest_assign(&new->value, sizeof(new->value));
        PMTest_flush(&new->value, sizeof(new->value));
        PMTest_fence();
}

I'm wondering if PMTest_assign -> PMTest_flush -> PMTest_fence can be kind of automated based on the instructions themselves, like PMDK's pmemcheck does. Is this possible, or do I have to manually instrument everything? Also am I correct in my translation to using PMTest?

Finally, let's say that I do not wish to sendTrace yet... for example, let's say that I have a non-blocking persistent data structure (so transactions are out of the question) that lazily persists certain fields; how does PMTest handle this? As well, during atomic operations, such as compare-and-swap, how should I go about instrumenting that?

Thanks in advance!

Hi, sihang
Error occurred when executing make.
/usr/bin/ld: build/objects/pmtest.o: undefined reference to symbol '__tls_get_addr@@GLIBC_2.3'
//usr/lib64/ld-linux-x86-64.so.2: error adding symbols: DSO missing from command line

CentOS Linux release 7.6.1810 (Core)
glibc-2.17-260.el7_6.3.x86_64
gcc/g++ version : 4.8.5

Hello,

Are there code examples available? Thanks!