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Date: Fri, 19 Jul 2013 11:55:15 -0700
From: "Darrick J. Wong" <darrick.wong@...cle.com>
To: Robert Yang <liezhi.yang@...driver.com>
Cc: tytso@....edu, dvhart@...ux.intel.com, linux-ext4@...r.kernel.org
Subject: Re: [PATCH 2/2] debugfs.c: do sparse copy when src is a sparse file
On Fri, Jul 19, 2013 at 10:17:37AM +0800, Robert Yang wrote:
> Let debugfs do sparse copy when src is a sparse file, just like
> "cp --sparse=auto"
>
> * For the
> #define IO_BUFSIZE 32*1024
>
> This is from coreutils-8.13/src/ioblksize.h (GPL V3):
> /* As of Mar 2009, 32KiB is determined to be the minimium
> blksize to best minimize system call overhead.
> This can be tested with this script with the results
> shown for a 1.7GHz pentium-m with 2GB of 400MHz DDR2 RAM:
Um.... GNU updated this to 64K a couple of years ago:
http://git.savannah.gnu.org/gitweb/?p=coreutils.git;a=blob;f=src/ioblksize.h;h=1ae93255e7d0ccf0855208c7ae5888209997bf16;hb=HEAD
Just for laughs I tried it on a T430 with an i5-3320M and 16G of DDR3-1600 RAM:
1024=3.7 GB/s
2048=7.1 GB/s
4096=8.8 GB/s
8192=14.9 GB/s
16384=14.3 GB/s
32768=13.4 GB/s
65536=15.8 GB/s
131072=20.7 GB/s
262144=16.4 GB/s
524288=15.9 GB/s
1048576=15.8 GB/s
2097152=15.1 GB/s
4194304=11.7 GB/s
8388608=9.9 GB/s
16777216=9.4 GB/s
33554432=9.3 GB/s
67108864=9.3 GB/s
134217728=8.8 GB/s
For that matter, a 2010-era i7-950/DDR3-1066 system showed this:
1024=3.4 GB/s
2048=5.6 GB/s
4096=7.8 GB/s
8192=9.5 GB/s
16384=10.8 GB/s
32768=11.4 GB/s
65536=11.6 GB/s
131072=12.2 GB/s
262144=11.9 GB/s
524288=12.3 GB/s
1048576=12.4 GB/s
2097152=12.5 GB/s
4194304=12.5 GB/s
8388608=10.3 GB/s
16777216=8.0 GB/s
33554432=7.6 GB/s
67108864=7.8 GB/s
134217728=7.5 GB/s
And for good measure, a cruddy old T2300 Core Duo from 2006 spat out this:
1024=1.1 GB/s
2048=2.1 GB/s
4096=3.6 GB/s
8192=5.0 GB/s
16384=6.3 GB/s
32768=6.5 GB/s
65536=6.6 GB/s
131072=7.0 GB/s
262144=7.1 GB/s
524288=7.1 GB/s
1048576=6.8 GB/s
2097152=4.4 GB/s
4194304=2.3 GB/s
8388608=2.0 GB/s
16777216=2.0 GB/s
33554432=2.0 GB/s
67108864=2.0 GB/s
134217728=1.9 GB/s
I suspect you could increase the buffer size to 128K (or possibly even BLKRAGET
size?) without much of a problem...
>
> for i in $(seq 0 10); do
> size=$((8*1024**3)) #ensure this is big enough
> bs=$((1024*2**$i))
> printf "%7s=" $bs
> dd bs=$bs if=/dev/zero of=/dev/null count=$(($size/$bs)) 2>&1 |
> sed -n 's/.* \([0-9.]* [GM]B\/s\)/\1/p'
> done
>
> 1024=734 MB/s
> 2048=1.3 GB/s
> 4096=2.4 GB/s
> 8192=3.5 GB/s
> 16384=3.9 GB/s
> 32768=5.2 GB/s
> 65536=5.3 GB/s
> 131072=5.5 GB/s
> 262144=5.7 GB/s
> 524288=5.7 GB/s
> 1048576=5.8 GB/s
>
> Note that this is to minimize system call overhead.
> Other values may be appropriate to minimize file system
> or disk overhead. For example on my current GNU/Linux system
> the readahead setting is 128KiB which was read using:
>
> file="."
> device=$(df -P --local "$file" | tail -n1 | cut -d' ' -f1)
> echo $(( $(blockdev --getra $device) * 512 ))
>
> However there isn't a portable way to get the above.
> In the future we could use the above method if available
> and default to io_blksize() if not.
> */
> enum { IO_BUFSIZE = 32*1024 };
>
> Signed-off-by: Robert Yang <liezhi.yang@...driver.com>
> Acked-by: Darren Hart <dvhart@...ux.intel.com>
> ---
> debugfs/debugfs.c | 70 +++++++++++++++++++++++++++++++++++++++++++++++--------
> 1 file changed, 60 insertions(+), 10 deletions(-)
>
> diff --git a/debugfs/debugfs.c b/debugfs/debugfs.c
> index b77d0b5..e443703 100644
> --- a/debugfs/debugfs.c
> +++ b/debugfs/debugfs.c
> @@ -37,6 +37,16 @@ extern char *optarg;
> #include "../version.h"
> #include "jfs_user.h"
>
> +/* 32KiB is the minimium blksize to best minimize system call overhead. */
> +#ifndef IO_BUFSIZE
> +#define IO_BUFSIZE 32*1024
> +#endif
> +
> +/* Block size for `st_blocks' */
> +#ifndef S_BLKSIZE
> +#define S_BLKSIZE 512
> +#endif
> +
> ss_request_table *extra_cmds;
> const char *debug_prog_name;
> int sci_idx;
> @@ -1571,14 +1581,17 @@ void do_find_free_inode(int argc, char *argv[])
> }
>
> #ifndef READ_ONLY
> -static errcode_t copy_file(int fd, ext2_ino_t newfile)
> +static errcode_t copy_file(int fd, ext2_ino_t newfile, int bufsize,
> + int make_holes, int *zero_written)
> {
> ext2_file_t e2_file;
> errcode_t retval;
> int got;
> unsigned int written;
> - char buf[8192];
> + char buf[bufsize];
...well, I guess it could be more of a problem if you put 128K on the stack.
--D
> char *ptr;
> + char *cp;
> + int count;
>
> retval = ext2fs_file_open(current_fs, newfile,
> EXT2_FILE_WRITE, &e2_file);
> @@ -1594,14 +1607,30 @@ static errcode_t copy_file(int fd, ext2_ino_t newfile)
> goto fail;
> }
> ptr = buf;
> + cp = ptr;
> + count = got;
> while (got > 0) {
> - retval = ext2fs_file_write(e2_file, ptr,
> - got, &written);
> - if (retval)
> - goto fail;
> -
> - got -= written;
> - ptr += written;
> + if (make_holes) {
> + /* Check whether all is zero */
> + while (count-- && *cp++ == 0)
> + continue;
> + if (count < 0) {
> + /* The whole block is zero, make a hole */
> + retval = ext2fs_file_lseek(e2_file, got, EXT2_SEEK_CUR, NULL);
> + if (retval)
> + goto fail;
> + got = 0;
> + }
> + }
> + /* Normal copy */
> + if (got > 0) {
> + *zero_written = 0;
> + retval = ext2fs_file_write(e2_file, ptr, got, &written);
> + if (retval)
> + goto fail;
> + got -= written;
> + ptr += written;
> + }
> }
> }
> retval = ext2fs_file_close(e2_file);
> @@ -1620,6 +1649,9 @@ void do_write(int argc, char *argv[])
> ext2_ino_t newfile;
> errcode_t retval;
> struct ext2_inode inode;
> + int bufsize = IO_BUFSIZE;
> + int make_holes = 0;
> + int zero_written = 1;
>
> if (common_args_process(argc, argv, 3, 3, "write",
> "<native file> <new file>", CHECK_FS_RW))
> @@ -1684,9 +1716,27 @@ void do_write(int argc, char *argv[])
> return;
> }
> if (LINUX_S_ISREG(inode.i_mode)) {
> - retval = copy_file(fd, newfile);
> + if (statbuf.st_blocks < statbuf.st_size / S_BLKSIZE) {
> + make_holes = 1;
> + /*
> + * Use I/O blocksize as buffer size when
> + * copying sparse files.
> + */
> + bufsize = statbuf.st_blksize;
> + }
> + retval = copy_file(fd, newfile, bufsize, make_holes, &zero_written);
> if (retval)
> com_err("copy_file", retval, 0);
> +
> + if ((inode.i_flags & EXT4_EXTENTS_FL) && zero_written) {
> + /*
> + * If no data is copied which indicateds that no write
> + * happens, we need to turn off the EXT4_EXTENTS_FL.
> + */
> + inode.i_flags &= ~EXT4_EXTENTS_FL;
> + if (debugfs_write_inode(newfile, &inode, argv[0]))
> + close(fd);
> + }
> }
> close(fd);
> }
> --
> 1.8.1.2
>
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