glusterfs-snapshot.git/xlators/performance/read-ahead, branch development

glusterfs: zerofill support

2013-11-11T05:25:49+00:00

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 
Signed-off-by: M. Mohan Kumar 
Reviewed-on: http://review.gluster.org/5327
Tested-by: Gluster Build System 
Reviewed-by: Vijay Bellur

glusterfs: discard (hole punch) support

2013-06-13T21:37:43+00:00

Add support for the DISCARD file operation. Discard punches a hole
in a file in the provided range. Block de-allocation is implemented
via fallocate() (as requested via fuse and passed on to the brick
fs) but a separate fop is created within gluster to emphasize the
fact that discard changes file data (the discarded region is
replaced with zeroes) and must invalidate caches where appropriate.

BUG: 963678
Change-Id: I34633a0bfff2187afeab4292a15f3cc9adf261af
Signed-off-by: Brian Foster 
Reviewed-on: http://review.gluster.org/5090
Tested-by: Gluster Build System 
Reviewed-by: Anand Avati

read-ahead: re-enable support for variable page size

2013-02-20T18:11:09+00:00

Support for variable size page-size was disabled with the introduction
of fixed size iobufs. Since the introduction of variable sized iobufs
there is no reason to not have configurable page-size in read-ahead.

This patch enables necessary changes in the translator for configurable
page-size.

Change-Id: I677d70fef50641eb041269aca92a088b9d4961cc
BUG: 764204
Signed-off-by: Anand Avati 
Reviewed-on: http://review.gluster.org/4526
Tested-by: Gluster Build System 
Reviewed-by: Raghavendra G

Use proper libtool option -avoid-version instead of bogus -avoidversion

2013-02-07T23:12:56+00:00

Change-Id: I1c9541058c7d07786539a3266ca125a6a15287d8
BUG: 859835
Signed-off-by: Anand Avati 
Original-author: Kacper Kowalik (Xarthisius) 
Signed-off-by: Kacper Kowalik (Xarthisius) 
Reviewed-on: http://review.gluster.org/3967
Tested-by: Gluster Build System

build: split CPPFLAGS from CFLAGS

2012-10-03T19:26:45+00:00

Automake provides a separate variable for preprocessor flags
(*_CPPFLAGS). They are already uses in a few places, so make it
consistent and use it everywhere. Note that cflags obtained from
pkg-config often are cppflags, which is why LIBXML2_CFLAGS moves with
into AM_CPPFLAGS, for example.

Change-Id: I15feed1d18b2ca497371271c4b5876d5ec6289dd
BUG: 862082
Original-author: Jan Engelhardt 
Signed-off-by: Jan Engelhardt 
Signed-off-by: Jeff Darcy 
Reviewed-on: http://review.gluster.org/4029
Tested-by: Gluster Build System 
Reviewed-by: Anand Avati

build: remove useless explicit -fPIC -shared from

2012-10-03T19:24:59+00:00

 CFLAGS

libtool will automatically add "-fPIC" to the compiler command line as
needed, so there is no need to specify it separately.

"-shared" is normally a linker flag and has an odd effect when used with
libtool --mode=compile, namely that it inhibits production of static
objects. For that however, using AC_DISABLE_STATIC is a lot simpler.

Change-Id: Ic4cba0fad18ffd985cf07f8d6951a976ae59a48f
BUG: 862082
Original-author: Jan Engelhardt 
Signed-off-by: Jan Engelhardt 
Signed-off-by: Jeff Darcy 
Reviewed-on: http://review.gluster.org/4027
Tested-by: Gluster Build System 
Reviewed-by: Anand Avati

build: remove -nostartfiles flag

2012-10-02T20:11:43+00:00

The "-nostartfiles" is a discouraged option and is documented to
potentially result in undesired behavior. Since I see no reason why it
should be in glusterfs, remove it.

Change-Id: I56f2b08874516ebad91447b2583ca2fb776bb7ab
BUG: 862082
Original-author: Jan Engelhardt 
Signed-off-by: Jan Engelhardt 
Signed-off-by: Jeff Darcy 
Reviewed-on: http://review.gluster.org/4018
Tested-by: Gluster Build System 
Reviewed-by: Anand Avati

build: consolidate common compilation flags into one variable

2012-10-01T23:44:50+00:00

Some -D flags are present in all files, so collect them.
This adds -D${GF_HOST_OS} to some compiler command lines,
but this should not be a problem.

Change-Id: I1aeb346143d4984c9cc4f2750c465ce09af1e6ca
BUG: 862082
Original-author: Jan Engelhardt 
Signed-off-by: Jan Engelhardt 
Signed-off-by: Jeff Darcy 
Reviewed-on: http://review.gluster.org/4013
Tested-by: Gluster Build System 
Reviewed-by: Anand Avati

performance/read-ahead: use pthread_mutex_trylock to hold mutex in statedumps

2012-08-01T21:33:58+00:00

Change-Id: I4491c96fc7d9879ba9040dcda3700c81d99ba184
BUG: 843796
Signed-off-by: Raghavendra Bhat 
Reviewed-on: http://review.gluster.com/3766
Tested-by: Gluster Build System 
Reviewed-by: Pranith Kumar Karampuri 
Reviewed-by: Anand Avati

remove useless if-before-free (and free-like) functions

2012-07-13T21:03:42+00:00

See comments in http://bugzilla.redhat.com/839925 for
the code to perform this change.

Signed-off-by: Jim Meyering 
BUG: 839925
Change-Id: I10e4ecff16c3749fe17c2831c516737e08a3205a
Reviewed-on: http://review.gluster.com/3661
Tested-by: Gluster Build System 
Reviewed-by: Anand Avati