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Commit 7c94ba27 authored by Andreas Gerstmayr's avatar Andreas Gerstmayr Committed by Ilya Dryomov
Browse files

ceph: set io_pages bdi hint 



This patch sets the io_pages bdi hint based on the rsize mount option.
Without this patch large buffered reads (request size > max readahead)
are processed sequentially in chunks of the readahead size (i.e. read
requests are sent out up to the readahead size, then the
do_generic_file_read() function waits until the first page is received).

With this patch read requests are sent out at once up to the size
specified in the rsize mount option (default: 64 MB).

Signed-off-by: default avatarAndreas Gerstmayr <andreas.gerstmayr@catalysts.cc>
Acked-by: default avatarJeff Layton <jlayton@redhat.com>
Signed-off-by: default avatarYan, Zheng <zyan@redhat.com>
parent 0fbc5360

Documentation/filesystems/ceph.txt

+2 −3
Original line number Diff line number Diff line
@@ -98,11 +98,10 @@ Mount Options 
	size.



  rsize=X

	Specify the maximum read size in bytes.  By default there is no

	maximum.

	Specify the maximum read size in bytes.  Default: 64 MB.



  rasize=X

	Specify the maximum readahead.

	Specify the maximum readahead.  Default: 8 MB.



  mount_timeout=X

	Specify the timeout value for mount (in seconds), in the case

fs/ceph/super.c

+8 −0
Original line number Diff line number Diff line
@@ -952,6 +952,14 @@ static int ceph_register_bdi(struct super_block *sb, 
		fsc->backing_dev_info.ra_pages =

			VM_MAX_READAHEAD * 1024 / PAGE_SIZE;



	if (fsc->mount_options->rsize > fsc->mount_options->rasize &&

	    fsc->mount_options->rsize >= PAGE_SIZE)

		fsc->backing_dev_info.io_pages =

			(fsc->mount_options->rsize + PAGE_SIZE - 1)

			>> PAGE_SHIFT;

	else if (fsc->mount_options->rsize == 0)

		fsc->backing_dev_info.io_pages = ULONG_MAX;



	err = bdi_register(&fsc->backing_dev_info, NULL, "ceph-%ld",

			   atomic_long_inc_return(&bdi_seq));

	if (!err)

fs/ceph/super.h

+2 −2
Original line number Diff line number Diff line
@@ -45,8 +45,8 @@ 
#define ceph_test_mount_opt(fsc, opt) \

	(!!((fsc)->mount_options->flags & CEPH_MOUNT_OPT_##opt))



#define CEPH_RSIZE_DEFAULT             0           /* max read size */

#define CEPH_RASIZE_DEFAULT            (8192*1024) /* readahead */

#define CEPH_RSIZE_DEFAULT              (64*1024*1024) /* max read size */

#define CEPH_RASIZE_DEFAULT             (8192*1024)    /* max readahead */

#define CEPH_MAX_READDIR_DEFAULT        1024

#define CEPH_MAX_READDIR_BYTES_DEFAULT  (512*1024)

#define CEPH_SNAPDIRNAME_DEFAULT        ".snap"