<feed xmlns='http://www.w3.org/2005/Atom'>
<title>glusterfs.git/xlators/performance, branch v3.5.0</title>
<subtitle></subtitle>
<link rel='alternate' type='text/html' href='http://git.gluster.org/cgit/glusterfs.git/'/>
<entry>
<title>performance/io-cache: reduce the severity of log-message</title>
<updated>2014-01-28T16:44:34+00:00</updated>
<author>
<name>Raghavendra G</name>
<email>rgowdapp@redhat.com</email>
</author>
<published>2014-01-03T05:53:02+00:00</published>
<link rel='alternate' type='text/html' href='http://git.gluster.org/cgit/glusterfs.git/commit/?id=d2743deed4c1ef2b06ac5e9889a882a8a52ad5e0'/>
<id>d2743deed4c1ef2b06ac5e9889a882a8a52ad5e0</id>
<content type='text'>
During a genuine error condition like network outage, the log grows
with redundant information.

Change-Id: I5a4f2f62da10ef656f14200c4c84a6917b1f0ddd
Signed-off-by: Raghavendra G &lt;rgowdapp@redhat.com&gt;
BUG: 1048084
Reviewed-on: http://review.gluster.org/6635
Reviewed-by: Pranith Kumar Karampuri &lt;pkarampu@redhat.com&gt;
Tested-by: Gluster Build System &lt;jenkins@build.gluster.com&gt;
Reviewed-by: Vijay Bellur &lt;vbellur@redhat.com&gt;
Reviewed-on: http://review.gluster.org/6815
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
During a genuine error condition like network outage, the log grows
with redundant information.

Change-Id: I5a4f2f62da10ef656f14200c4c84a6917b1f0ddd
Signed-off-by: Raghavendra G &lt;rgowdapp@redhat.com&gt;
BUG: 1048084
Reviewed-on: http://review.gluster.org/6635
Reviewed-by: Pranith Kumar Karampuri &lt;pkarampu@redhat.com&gt;
Tested-by: Gluster Build System &lt;jenkins@build.gluster.com&gt;
Reviewed-by: Vijay Bellur &lt;vbellur@redhat.com&gt;
Reviewed-on: http://review.gluster.org/6815
</pre>
</div>
</content>
</entry>
<entry>
<title>write-behind: handle iobref_merge() error gracefully</title>
<updated>2013-11-26T18:32:00+00:00</updated>
<author>
<name>Anand Avati</name>
<email>avati@redhat.com</email>
</author>
<published>2013-11-25T11:13:17+00:00</published>
<link rel='alternate' type='text/html' href='http://git.gluster.org/cgit/glusterfs.git/commit/?id=d4c9d342f64636304720d0091a605c85ea9f0e4d'/>
<id>d4c9d342f64636304720d0091a605c85ea9f0e4d</id>
<content type='text'>
.. by UNWINDing ENOMEM error, rather than crashing.

Change-Id: Ica2d6399eaf7e381e7ebc41155620559c139c4d3
BUG: 1034398
Signed-off-by: Anand Avati &lt;avati@redhat.com&gt;
Reviewed-on: http://review.gluster.org/6349
Tested-by: Gluster Build System &lt;jenkins@build.gluster.com&gt;
Reviewed-by: Amar Tumballi &lt;amarts@gmail.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
.. by UNWINDing ENOMEM error, rather than crashing.

Change-Id: Ica2d6399eaf7e381e7ebc41155620559c139c4d3
BUG: 1034398
Signed-off-by: Anand Avati &lt;avati@redhat.com&gt;
Reviewed-on: http://review.gluster.org/6349
Tested-by: Gluster Build System &lt;jenkins@build.gluster.com&gt;
Reviewed-by: Amar Tumballi &lt;amarts@gmail.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>io-cache: handle iobref_merge() error gracefully</title>
<updated>2013-11-26T18:31:48+00:00</updated>
<author>
<name>Anand Avati</name>
<email>avati@redhat.com</email>
</author>
<published>2013-11-25T11:19:11+00:00</published>
<link rel='alternate' type='text/html' href='http://git.gluster.org/cgit/glusterfs.git/commit/?id=e3f80f53b536eba17e35c184e9da3e4d59c30b58'/>
<id>e3f80f53b536eba17e35c184e9da3e4d59c30b58</id>
<content type='text'>
.. by UNWINDing ENOMEM, rather than leaving pointer in vector pointing
to stale memory.

Change-Id: I7f3917ac056fae144f845c9d123233e91e278187
BUG: 1034398
Signed-off-by: Anand Avati &lt;avati@redhat.com&gt;
Reviewed-on: http://review.gluster.org/6351
Tested-by: Gluster Build System &lt;jenkins@build.gluster.com&gt;
Reviewed-by: Amar Tumballi &lt;amarts@gmail.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
.. by UNWINDing ENOMEM, rather than leaving pointer in vector pointing
to stale memory.

Change-Id: I7f3917ac056fae144f845c9d123233e91e278187
BUG: 1034398
Signed-off-by: Anand Avati &lt;avati@redhat.com&gt;
Reviewed-on: http://review.gluster.org/6351
Tested-by: Gluster Build System &lt;jenkins@build.gluster.com&gt;
Reviewed-by: Amar Tumballi &lt;amarts@gmail.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>read-ahead: handle iobref_merge() error gracefully</title>
<updated>2013-11-26T18:31:40+00:00</updated>
<author>
<name>Anand Avati</name>
<email>avati@redhat.com</email>
</author>
<published>2013-11-25T11:16:49+00:00</published>
<link rel='alternate' type='text/html' href='http://git.gluster.org/cgit/glusterfs.git/commit/?id=2a18e2426419cbab2f98368b3306fd37958394d2'/>
<id>2a18e2426419cbab2f98368b3306fd37958394d2</id>
<content type='text'>
.. by UNWINDing ENOMEM rather than leaving pointers in vector which
points to unref'ed (or even worse, re-used) iobufs.

Change-Id: I849d8cbe5fc02ee992d4e28b7212c49aad4925c7
BUG: 1034398
Signed-off-by: Anand Avati &lt;avati@redhat.com&gt;
Reviewed-on: http://review.gluster.org/6350
Tested-by: Gluster Build System &lt;jenkins@build.gluster.com&gt;
Reviewed-by: Amar Tumballi &lt;amarts@gmail.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
.. by UNWINDing ENOMEM rather than leaving pointers in vector which
points to unref'ed (or even worse, re-used) iobufs.

Change-Id: I849d8cbe5fc02ee992d4e28b7212c49aad4925c7
BUG: 1034398
Signed-off-by: Anand Avati &lt;avati@redhat.com&gt;
Reviewed-on: http://review.gluster.org/6350
Tested-by: Gluster Build System &lt;jenkins@build.gluster.com&gt;
Reviewed-by: Amar Tumballi &lt;amarts@gmail.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>zerofill: Change the type of len argument of glfs_zerofill() to off_t</title>
<updated>2013-11-15T07:29:48+00:00</updated>
<author>
<name>Bharata B Rao</name>
<email>bharata@linux.vnet.ibm.com</email>
</author>
<published>2013-11-15T04:41:58+00:00</published>
<link rel='alternate' type='text/html' href='http://git.gluster.org/cgit/glusterfs.git/commit/?id=884a668a9c3e12e17d64ebd5ccd9fbf3d203fd1e'/>
<id>884a668a9c3e12e17d64ebd5ccd9fbf3d203fd1e</id>
<content type='text'>
glfs_zerofill() can be potentially called to zero-out entire file and
hence allow for bigger value of length parameter.

Change-Id: I75f1d11af298915049a3f3a7cb3890a2d72fca63
BUG: 1028673
Signed-off-by: Bharata B Rao &lt;bharata@linux.vnet.ibm.com&gt;
Reviewed-on: http://review.gluster.org/6266
Tested-by: Gluster Build System &lt;jenkins@build.gluster.com&gt;
Reviewed-by: M. Mohan Kumar &lt;mohan@in.ibm.com&gt;
Tested-by: M. Mohan Kumar &lt;mohan@in.ibm.com&gt;
Reviewed-by: Anand Avati &lt;avati@redhat.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
glfs_zerofill() can be potentially called to zero-out entire file and
hence allow for bigger value of length parameter.

Change-Id: I75f1d11af298915049a3f3a7cb3890a2d72fca63
BUG: 1028673
Signed-off-by: Bharata B Rao &lt;bharata@linux.vnet.ibm.com&gt;
Reviewed-on: http://review.gluster.org/6266
Tested-by: Gluster Build System &lt;jenkins@build.gluster.com&gt;
Reviewed-by: M. Mohan Kumar &lt;mohan@in.ibm.com&gt;
Tested-by: M. Mohan Kumar &lt;mohan@in.ibm.com&gt;
Reviewed-by: Anand Avati &lt;avati@redhat.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>libglusterfs/inode: introduce new APIs for ctx handling</title>
<updated>2013-11-13T19:43:48+00:00</updated>
<author>
<name>Amar Tumballi</name>
<email>amarts@redhat.com</email>
</author>
<published>2013-09-10T12:10:04+00:00</published>
<link rel='alternate' type='text/html' href='http://git.gluster.org/cgit/glusterfs.git/commit/?id=5d7560e11e371919c97f78381c0d0c90885ce80f'/>
<id>5d7560e11e371919c97f78381c0d0c90885ce80f</id>
<content type='text'>
* inode_ctx_reset{0,1,2}() for reseting value1, value2, and both respectively
* inode_ctx_get0() - to get the first value only
* inode_ctx_set0() - to set the first value only
* inode_ctx_get1() - to get the second value only
* inode_ctx_set1() - to set the second value only

Change-Id: I4dfbdac81d6a3f4e5784e060c76edabb1692ce03
Signed-off-by: Amar Tumballi &lt;amarts@redhat.com&gt;
Reviewed-on: http://review.gluster.org/5890
Reviewed-by: Anand Avati &lt;avati@redhat.com&gt;
Tested-by: Anand Avati &lt;avati@redhat.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
* inode_ctx_reset{0,1,2}() for reseting value1, value2, and both respectively
* inode_ctx_get0() - to get the first value only
* inode_ctx_set0() - to set the first value only
* inode_ctx_get1() - to get the second value only
* inode_ctx_set1() - to set the second value only

Change-Id: I4dfbdac81d6a3f4e5784e060c76edabb1692ce03
Signed-off-by: Amar Tumballi &lt;amarts@redhat.com&gt;
Reviewed-on: http://review.gluster.org/5890
Reviewed-by: Anand Avati &lt;avati@redhat.com&gt;
Tested-by: Anand Avati &lt;avati@redhat.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>glusterfs: zerofill support</title>
<updated>2013-11-11T05:25:49+00:00</updated>
<author>
<name>M. Mohan Kumar</name>
<email>mohan@in.ibm.com</email>
</author>
<published>2013-11-09T09:21:53+00:00</published>
<link rel='alternate' type='text/html' href='http://git.gluster.org/cgit/glusterfs.git/commit/?id=c8fef37c5d566c906728b5f6f27baaa9a8d2a20d'/>
<id>c8fef37c5d566c906728b5f6f27baaa9a8d2a20d</id>
<content type='text'>
Add support for a new ZEROFILL fop. Zerofill writes zeroes to a file in
the specified range. This fop will be useful when a whole file needs to
be initialized with zero (could be useful for zero filled VM disk image
provisioning or  during scrubbing of VM disk images).

Client/application can issue this FOP for zeroing out. Gluster server
will zero out required range of bytes ie server offloaded zeroing. In
the absence of this fop,  client/application has to repetitively issue
write (zero) fop to the server, which is very inefficient method because
of the overheads involved in RPC calls  and acknowledgements.

WRITESAME is a  SCSI T10 command that takes a block of data as input and
writes the same data to other blocks and this write is handled
completely within the storage and hence is known as offload . Linux ,now
has support for SCSI WRITESAME command which is exposed to the user in
the form of BLKZEROOUT ioctl.  BD Xlator can exploit BLKZEROOUT ioctl to
implement this fop. Thus zeroing out operations can be completely
offloaded to the storage device , making it highly efficient.

The fop takes two arguments offset and size. It zeroes out 'size' number
of bytes in an opened file starting from 'offset' position.

This patch adds zerofill support to the following areas:
	- libglusterfs
	- io-stats
	- performance/md-cache,open-behind
	- quota
	- cluster/afr,dht,stripe
	- rpc/xdr
	- protocol/client,server
	- io-threads
	- marker
	- storage/posix
	- libgfapi

Client applications can exloit this fop by using glfs_zerofill introduced in
libgfapi.FUSE support to this fop has not been added as there is no system call
for this fop.

Changes from previous version 3:
* Removed redundant memory failure log messages

Changes from previous version 2:
* Rebased and fixed build error

Changes from previous version 1:
* Rebased for latest master

TODO :
     * Add zerofill support to trace xlator
     * Expose zerofill capability as part of gluster volume info

Here is a performance comparison of server offloaded zeofill vs zeroing
out using repeated writes.

[root@llmvm02 remote]# time ./offloaded aakash-test log 20

real	3m34.155s
user	0m0.018s
sys	0m0.040s
[root@llmvm02 remote]# time ./manually aakash-test log 20

real	4m23.043s
user	0m2.197s
sys	0m14.457s
[root@llmvm02 remote]# time ./offloaded aakash-test log 25;

real	4m28.363s
user	0m0.021s
sys	0m0.025s
[root@llmvm02 remote]# time ./manually aakash-test log 25

real	5m34.278s
user	0m2.957s
sys	0m18.808s

The argument log is a file which we want to set for logging purpose and
the third argument is size in GB .

As we can see there is a performance improvement of around 20% with this
fop.

Change-Id: I081159f5f7edde0ddb78169fb4c21c776ec91a18
BUG: 1028673
Signed-off-by: Aakash Lal Das &lt;aakash@linux.vnet.ibm.com&gt;
Signed-off-by: M. Mohan Kumar &lt;mohan@in.ibm.com&gt;
Reviewed-on: http://review.gluster.org/5327
Tested-by: Gluster Build System &lt;jenkins@build.gluster.com&gt;
Reviewed-by: Vijay Bellur &lt;vbellur@redhat.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Add support for a new ZEROFILL fop. Zerofill writes zeroes to a file in
the specified range. This fop will be useful when a whole file needs to
be initialized with zero (could be useful for zero filled VM disk image
provisioning or  during scrubbing of VM disk images).

Client/application can issue this FOP for zeroing out. Gluster server
will zero out required range of bytes ie server offloaded zeroing. In
the absence of this fop,  client/application has to repetitively issue
write (zero) fop to the server, which is very inefficient method because
of the overheads involved in RPC calls  and acknowledgements.

WRITESAME is a  SCSI T10 command that takes a block of data as input and
writes the same data to other blocks and this write is handled
completely within the storage and hence is known as offload . Linux ,now
has support for SCSI WRITESAME command which is exposed to the user in
the form of BLKZEROOUT ioctl.  BD Xlator can exploit BLKZEROOUT ioctl to
implement this fop. Thus zeroing out operations can be completely
offloaded to the storage device , making it highly efficient.

The fop takes two arguments offset and size. It zeroes out 'size' number
of bytes in an opened file starting from 'offset' position.

This patch adds zerofill support to the following areas:
	- libglusterfs
	- io-stats
	- performance/md-cache,open-behind
	- quota
	- cluster/afr,dht,stripe
	- rpc/xdr
	- protocol/client,server
	- io-threads
	- marker
	- storage/posix
	- libgfapi

Client applications can exloit this fop by using glfs_zerofill introduced in
libgfapi.FUSE support to this fop has not been added as there is no system call
for this fop.

Changes from previous version 3:
* Removed redundant memory failure log messages

Changes from previous version 2:
* Rebased and fixed build error

Changes from previous version 1:
* Rebased for latest master

TODO :
     * Add zerofill support to trace xlator
     * Expose zerofill capability as part of gluster volume info

Here is a performance comparison of server offloaded zeofill vs zeroing
out using repeated writes.

[root@llmvm02 remote]# time ./offloaded aakash-test log 20

real	3m34.155s
user	0m0.018s
sys	0m0.040s
[root@llmvm02 remote]# time ./manually aakash-test log 20

real	4m23.043s
user	0m2.197s
sys	0m14.457s
[root@llmvm02 remote]# time ./offloaded aakash-test log 25;

real	4m28.363s
user	0m0.021s
sys	0m0.025s
[root@llmvm02 remote]# time ./manually aakash-test log 25

real	5m34.278s
user	0m2.957s
sys	0m18.808s

The argument log is a file which we want to set for logging purpose and
the third argument is size in GB .

As we can see there is a performance improvement of around 20% with this
fop.

Change-Id: I081159f5f7edde0ddb78169fb4c21c776ec91a18
BUG: 1028673
Signed-off-by: Aakash Lal Das &lt;aakash@linux.vnet.ibm.com&gt;
Signed-off-by: M. Mohan Kumar &lt;mohan@in.ibm.com&gt;
Reviewed-on: http://review.gluster.org/5327
Tested-by: Gluster Build System &lt;jenkins@build.gluster.com&gt;
Reviewed-by: Vijay Bellur &lt;vbellur@redhat.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>gNFS: Incorrect NFS ACL encoding for XFS</title>
<updated>2013-09-29T23:54:37+00:00</updated>
<author>
<name>Santosh Kumar Pradhan</name>
<email>spradhan@redhat.com</email>
</author>
<published>2013-09-19T06:31:38+00:00</published>
<link rel='alternate' type='text/html' href='http://git.gluster.org/cgit/glusterfs.git/commit/?id=e9554f7792d893f0ea8afe368829f9944ef52bdf'/>
<id>e9554f7792d893f0ea8afe368829f9944ef52bdf</id>
<content type='text'>
Problem:
Incorrect NFS ACL encoding causes "system.posix_acl_default"
setxattr failure on bricks on XFS file system. XFS (potentially
others?) doesn't understand when the 0x10 prefix is added to the
ACL type field for default ACLs (which the Linux NFS client adds)
which causes setfacl()-&gt;setxattr() to fail silently. NFS client
adds NFS_ACL_DEFAULT(0x1000) for default ACL.

FIX:
Mask the prefix (added by NFS client) OFF, so the setfacl is not
rejected when it hits the FS.

Original patch by: "Richard Wareing"

Change-Id: I17ad27d84f030cdea8396eb667ee031f0d41b396
BUG: 1009210
Signed-off-by: Santosh Kumar Pradhan &lt;spradhan@redhat.com&gt;
Reviewed-on: http://review.gluster.org/5980
Reviewed-by: Amar Tumballi &lt;amarts@redhat.com&gt;
Tested-by: Gluster Build System &lt;jenkins@build.gluster.com&gt;
Reviewed-by: Anand Avati &lt;avati@redhat.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Problem:
Incorrect NFS ACL encoding causes "system.posix_acl_default"
setxattr failure on bricks on XFS file system. XFS (potentially
others?) doesn't understand when the 0x10 prefix is added to the
ACL type field for default ACLs (which the Linux NFS client adds)
which causes setfacl()-&gt;setxattr() to fail silently. NFS client
adds NFS_ACL_DEFAULT(0x1000) for default ACL.

FIX:
Mask the prefix (added by NFS client) OFF, so the setfacl is not
rejected when it hits the FS.

Original patch by: "Richard Wareing"

Change-Id: I17ad27d84f030cdea8396eb667ee031f0d41b396
BUG: 1009210
Signed-off-by: Santosh Kumar Pradhan &lt;spradhan@redhat.com&gt;
Reviewed-on: http://review.gluster.org/5980
Reviewed-by: Amar Tumballi &lt;amarts@redhat.com&gt;
Tested-by: Gluster Build System &lt;jenkins@build.gluster.com&gt;
Reviewed-by: Anand Avati &lt;avati@redhat.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>core: block unused signals in created threads</title>
<updated>2013-09-25T08:33:16+00:00</updated>
<author>
<name>Anand Avati</name>
<email>avati@redhat.com</email>
</author>
<published>2013-09-24T16:45:08+00:00</published>
<link rel='alternate' type='text/html' href='http://git.gluster.org/cgit/glusterfs.git/commit/?id=84fa8af38d2eab0f72349abb8136811bd3e96570'/>
<id>84fa8af38d2eab0f72349abb8136811bd3e96570</id>
<content type='text'>
Block all signal except those which are set for explicit handling
in glusterfs_signals_setup(). Since thread spawning code in
libglusterfs and xlators can get called from application threads
when used through libgfapi, it is necessary to do this blocking.

Change-Id: Ia320f80521a83d2edcda50b9ad414583a0175281
BUG: 1011662
Signed-off-by: Anand Avati &lt;avati@redhat.com&gt;
Reviewed-on: http://review.gluster.org/5995
Tested-by: Gluster Build System &lt;jenkins@build.gluster.com&gt;
Reviewed-by: Amar Tumballi &lt;amarts@redhat.com&gt;
Reviewed-by: Vijay Bellur &lt;vbellur@redhat.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Block all signal except those which are set for explicit handling
in glusterfs_signals_setup(). Since thread spawning code in
libglusterfs and xlators can get called from application threads
when used through libgfapi, it is necessary to do this blocking.

Change-Id: Ia320f80521a83d2edcda50b9ad414583a0175281
BUG: 1011662
Signed-off-by: Anand Avati &lt;avati@redhat.com&gt;
Reviewed-on: http://review.gluster.org/5995
Tested-by: Gluster Build System &lt;jenkins@build.gluster.com&gt;
Reviewed-by: Amar Tumballi &lt;amarts@redhat.com&gt;
Reviewed-by: Vijay Bellur &lt;vbellur@redhat.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>performance/readdir-ahead: introduce directory read-ahead translator</title>
<updated>2013-09-04T16:04:15+00:00</updated>
<author>
<name>Brian Foster</name>
<email>bfoster@redhat.com</email>
</author>
<published>2013-07-02T14:47:00+00:00</published>
<link rel='alternate' type='text/html' href='http://git.gluster.org/cgit/glusterfs.git/commit/?id=3b23f9acae02e6be192c00fc410a4d15974f5343'/>
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This is a translator to improve the performance of typical,
sequential directory reads (i.e., ls). readdir-ahead begins
preloading the contents of a directory on open and serves readdir
requests from the preloaded content. readdir-ahead is currently
implemented to only handle the single threaded directory read
case.

readdir-ahead is currently disabled by default. It can be enabled
with the following command:

	gluster volume set &lt;volname&gt; readdir-ahead on

The following are results of a getdents test on a single brick
volume.

Test info:

- Single VM, gluster client/server.
- Volume mounted with native client using --gid-timeout=2.
- getdents on single directory with 100k 0-byte files.

Test results:

- !readdir-ahead

read 3120080 bytes from offset 0
3 MiB, 4348 ops, 0:00:07.00 (416.590 KiB/sec and 594.4737 ops/sec)

- readdir-ahead

read 3120080 bytes from offset 0
3 MiB, 4348 ops, 0:00:03.00 (820.116 KiB/sec and 1170.3043 ops/sec)

BUG: 980517
Change-Id: Ieceb9e1eb47d1d5b5af8da2bf03839537364653f
Signed-off-by: Brian Foster &lt;bfoster@redhat.com&gt;
Reviewed-on: http://review.gluster.org/4519
Tested-by: Gluster Build System &lt;jenkins@build.gluster.com&gt;
Reviewed-by: Anand Avati &lt;avati@redhat.com&gt;
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This is a translator to improve the performance of typical,
sequential directory reads (i.e., ls). readdir-ahead begins
preloading the contents of a directory on open and serves readdir
requests from the preloaded content. readdir-ahead is currently
implemented to only handle the single threaded directory read
case.

readdir-ahead is currently disabled by default. It can be enabled
with the following command:

	gluster volume set &lt;volname&gt; readdir-ahead on

The following are results of a getdents test on a single brick
volume.

Test info:

- Single VM, gluster client/server.
- Volume mounted with native client using --gid-timeout=2.
- getdents on single directory with 100k 0-byte files.

Test results:

- !readdir-ahead

read 3120080 bytes from offset 0
3 MiB, 4348 ops, 0:00:07.00 (416.590 KiB/sec and 594.4737 ops/sec)

- readdir-ahead

read 3120080 bytes from offset 0
3 MiB, 4348 ops, 0:00:03.00 (820.116 KiB/sec and 1170.3043 ops/sec)

BUG: 980517
Change-Id: Ieceb9e1eb47d1d5b5af8da2bf03839537364653f
Signed-off-by: Brian Foster &lt;bfoster@redhat.com&gt;
Reviewed-on: http://review.gluster.org/4519
Tested-by: Gluster Build System &lt;jenkins@build.gluster.com&gt;
Reviewed-by: Anand Avati &lt;avati@redhat.com&gt;
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