On 05/01/2012 05:59 PM, Pádraig Brady wrote: > Now many coreutils already provide such a hint to the kernel: > http://git.sv.gnu.org/gitweb/?p=coreutils.git;a=commit;h=47076e3c > But copy.c does not currently. I'm not sure why I didn't > do it for copy.c now, but I look into adding it.
The attached seems to give another 5% speedup! $ dd bs=1MB count=200 if=/dev/zero of=file.in $ dd of=file.in oflag=nocache conv=notrunc,fdatasync count=0 $ time ./cp-before file.in /dev/shm/; rm /dev/shm/file.in real 0m0.843s user 0m0.005s sys 0m0.417s $ dd of=file.in oflag=nocache conv=notrunc,fdatasync count=0 $ time ./cp-before file.in /dev/shm/; rm /dev/shm/file.in real 0m0.856s user 0m0.002s sys 0m0.422s $ dd of=file.in oflag=nocache conv=notrunc,fdatasync count=0 $ time ./cp-after file.in /dev/shm/; rm /dev/shm/file.in real 0m0.809s user 0m0.006s sys 0m0.373s $ dd of=file.in oflag=nocache conv=notrunc,fdatasync count=0 $ time ./cp-after file.in /dev/shm/; rm /dev/shm/file.in real 0m0.804s user 0m0.007s sys 0m0.405s cheers, Pádraig.
>From 24e6311c53f40e874854e1574ee1c8f2de161ab2 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?P=C3=A1draig=20Brady?= <[email protected]> Date: Tue, 1 May 2012 21:50:49 +0100 Subject: [PATCH] cp,mv,install: provide POSIX_FADV_SEQUENTIAL hint to input This was inadvertently omitted from v8.5-104-g47076e3, and gives the same 5% speedup when copying from an SSD. * src/copy.c (copy_internal): Apply the FADVISE_SEQUENTIAL hint. --- src/copy.c | 3 +++ 1 files changed, 3 insertions(+), 0 deletions(-) diff --git a/src/copy.c b/src/copy.c index 414fbe0..00d1c34 100644 --- a/src/copy.c +++ b/src/copy.c @@ -39,6 +39,7 @@ #include "cp-hash.h" #include "extent-scan.h" #include "error.h" +#include "fadvise.h" #include "fcntl--.h" #include "fiemap.h" #include "file-set.h" @@ -980,6 +981,8 @@ copy_reg (char const *src_name, char const *dst_name, size_t buf_alignment_slop = sizeof (word) + buf_alignment - 1; size_t buf_size = io_blksize (sb); + fdadvise (source_desc, 0, 0, FADVISE_SEQUENTIAL); + /* Deal with sparse files. */ bool make_holes = false; bool sparse_src = false; -- 1.7.6.4
