glusterfs.git/libglusterfs/src/fd.h, branch v4.1.7

glusterfs: Use gcc builtin ATOMIC operator to increase/decreate refcount.

2017-12-12T09:05:56+00:00

Problem: In glusterfs code base we call mutex_lock/unlock to take
         reference/dereference for a object.Sometime it could be
         reason for lock contention also.

Solution: There is no need to use mutex to increase/decrease ref
          counter, instead of using mutex use gcc builtin ATOMIC
          operation.

Test:   I have not observed yet how much performance gain after apply
        this patch specific to glusterfs but i have tested same
        with below small program(mutex and atomic both) and
        get good difference.

static int numOuterLoops;
static void *
threadFunc(void *arg)
{
    int j;

    for (j = 0; j < numOuterLoops; j++) {
            __atomic_add_fetch (&glob, 1,__ATOMIC_ACQ_REL);
    }
    return NULL;
}

int
main(int argc, char *argv[])
{
    int opt, s, j;
    int numThreads;
    pthread_t *thread;
    int verbose;
    int64_t n = 0;

    if (argc < 2 ) {
     printf(" Please provide 2 args Num of threads && Outer Loop\n");
     exit (-1);
    }
    numThreads = atoi(argv[1]);
    numOuterLoops = atoi (argv[2]);

    if (1) {
        printf("\tthreads: %d; outer loops: %d;\n",
                numThreads, numOuterLoops);
    }

    thread = calloc(numThreads, sizeof(pthread_t));
    if (thread == NULL) {
        printf ("calloc error so exit\n");
        exit (-1);
    }

    __atomic_store (&glob, &n, __ATOMIC_RELEASE);
    for (j = 0; j < numThreads; j++) {
        s = pthread_create(&thread[j], NULL, threadFunc, NULL);
        if (s != 0) {
            printf ("pthread_create failed so exit\n");
            exit (-1);
        }
    }

    for (j = 0; j < numThreads; j++) {
        s = pthread_join(thread[j], NULL);
        if (s != 0) {
            printf ("pthread_join failed so exit\n");
            exit (-1);
        }
    }
    printf("glob value is %ld\n",__atomic_load_n (&glob,__ATOMIC_RELAXED));

    exit(0);
}

   time ./thr_count 800 800000
   threads: 800; outer loops: 800000;
   glob value is 640000000

real	1m10.288s
user	0m57.269s
sys	3m31.565s

time ./thr_count_atomic 800 800000
     threads: 800; outer loops: 800000;
glob value is 640000000

real	0m20.313s
user	1m20.558s
sys	0m0.028

Change-Id: Ie5030a52ea264875e002e108dd4b207b15ab7cc7
Signed-off-by: Mohit Agrawal

libglusterfs: use rwlock for fdtable

2017-11-30T12:34:25+00:00

To resolve a fd from client requests, need to take a mutex lock for the
fdtable to do the lookup. When a client is busy doing read and write,
the mutex lock could introduce contention. Therefore, use rwlock instead
of mutex to reduce the contention.

Change-Id: Ic833aed738a178a7ea1abafed7eb13814989d28c
BUG: 1518582
Signed-off-by: Zhang Huan

cluster/ec: Fix invalid __fd_unref() call

2016-06-13T12:14:38+00:00

__fd_unref() doesn't do any cleanup, so it cannot be called to release
fd references, specially if it's the last reference.

The code has been changed to avoid a call to this function.

In the previous version we always tried to keep the newest fd in the
ec_lock_t structure. However this is not necessary. We'll always keep
one reference to an open file on the same inode. It's irrelevant if
the reference is new or old.

The function __fd_unref() has also been removed from fd.h to avoid being
used in the future since it's useless as it's defined now.

Change-Id: Ia728777fc8e464758d5ea4d3bf020f0603919039
BUG: 1344396
Signed-off-by: Xavier Hernandez 
Reviewed-on: http://review.gluster.org/14683
NetBSD-regression: NetBSD Build System 
Smoke: Gluster Build System 
CentOS-regression: Gluster Build System 
Reviewed-by: Ashish Pandey 
Reviewed-by: Jeff Darcy

core, shard: Make shards inherit main file's O_DIRECT flag if present

2016-06-07T07:19:26+00:00

If the application opens a file with O_DIRECT, the shards'
anon fds would also need to inherit the flag. Towards this,
shard xl would be passing the odirect flag in the @flags parameter
to the WRITEV fop. This will be used in anon fd resolution
and subsequent opening by posix xl.

Change-Id: Iddb75c9ed14ce5a8c5d2128ad09b749f46e3b0c2
BUG: 1342171
Signed-off-by: Krutika Dhananjay 
Reviewed-on: http://review.gluster.org/14191
Tested-by: Pranith Kumar Karampuri 
Smoke: Gluster Build System 
CentOS-regression: Gluster Build System 
NetBSD-regression: NetBSD Build System 
Reviewed-by: Pranith Kumar Karampuri

cluster/ec: Allow read fops to be processed in parallel

2015-08-29T10:55:28+00:00

Currently ec only sends a single read request at a time for a given
inode. Since reads do not interfere between them, this patch allows
multiple concurrent read requests to be sent in parallel.

Change-Id: If853430482a71767823f39ea70ff89797019d46b
BUG: 1245689
Signed-off-by: Xavier Hernandez 
Reviewed-on: http://review.gluster.org/11742
Tested-by: NetBSD Build System 
Reviewed-by: Pranith Kumar Karampuri 
Tested-by: Gluster Build System

libglusterfs: Even anonymous fds must have fd->flags set

2015-07-20T10:48:19+00:00

We do not set the same flags to anonymous fd that posix uses to open
an anonymous fd in the backend. If there are any xlators which rely on
these flags for their operation they may not work well.

Add proper flags to anonymous fds at the time of their creation and
refer to them for subsequent operations.

Change-Id: Ia99b7ea7d38839f099c7b4aae3c7ead123bc8c67
BUG: 1211221
Signed-off-by: Raghavendra Talur 
Reviewed-on: http://review.gluster.org/10219
Tested-by: NetBSD Build System 
Reviewed-by: soumya k 
Reviewed-by: Poornima G 
Tested-by: Gluster Build System 
Reviewed-by: Rajesh Joseph 
Reviewed-by: Niels de Vos 
Reviewed-by: Raghavendra Bhat 
Reviewed-by: Raghavendra G

build: do not #include "config.h" in each file

2015-05-29T12:43:17+00:00

Instead of including config.h in each file, and have the additional
config.h included from the compiler commandline (-include option).

When a .c file tests for a certain #define, and config.h was not
included, incorrect assumtions were made. With this change, it can not
happen again.

BUG: 1222319
Change-Id: I4f9097b8740b81ecfe8b218d52ca50361f74cb64
Signed-off-by: Niels de Vos 
Reviewed-on: http://review.gluster.org/10808
Tested-by: Gluster Build System 
Tested-by: NetBSD Build System
Reviewed-by: Kaleb KEITHLEY 
Reviewed-by: Pranith Kumar Karampuri

cluster/afr: Perform delayed changelog wakeups for anon fd

2013-06-20T08:44:37+00:00

Problem:
Nfs xlator never does open on a file for performing writes,
afr does not perform changelog wakeup for this fd so operations
which do metadata operations as soon as the data operations are
completed perceive a delay of 'post-op-delay-secs'.

Fix:
Perform changelog wakeup on anon-fd if the fd with same pid is
not present in inode-list.

Note:
This approach is a short-term fix. A proper fix needs a new domain
for taking metadata locks so that data/metadata locks don't compete
with each other.

Change-Id: I253afb289eadf30c7951e56fb2c4840d7132f5e4
BUG: 966018
Signed-off-by: Pranith Kumar K 
Reviewed-on: http://review.gluster.org/5066
Tested-by: Gluster Build System 
Reviewed-by: Vijay Bellur

protocol/client: Periodically attempt reopens

2013-02-03T19:33:31+00:00

If the brick is taken down and the hard disk is replaced
and the brick is brought back up, the re-opens of the open-fds
will fail because the file is not present on the brick.
Re-opens are not attempted even if the files are re-created by
self-heal until the brick is brought down after the files are
re-created and brought back up. This is a problem with a VM-store
in a replica-setup.  Until the fd is re-opened the writes will
never happen on the brick where the hard-disk is replaced.
To handle this situation gracefully, client xlator is enhanced
to perform finodelk, fxattrop, writev, readv using anonymous fds
if the file is yet to be re-opened. If the fop succeeds then client
xlator attempts re-open.

Change-Id: I1cc6d1bbf8227cd996868ab2ed0a57fb05e00017
BUG: 821056
Signed-off-by: Pranith Kumar K 
Reviewed-on: http://review.gluster.org/4358
Tested-by: Gluster Build System 
Reviewed-by: Jeff Darcy

fd: expose __fd_ctx_del symbol

2013-01-29T00:45:30+00:00

used by open-behind for deleting context in locked critical region

Change-Id: I3380152211fed6aacbb719468b720376e6ec1e7c
BUG: 846240
Signed-off-by: Anand Avati 
Reviewed-on: http://review.gluster.org/4405
Tested-by: Gluster Build System