The patch titled
readahead: initial method - expected read size - fix fastcall
has been added to the -mm tree. Its filename is
readahead-call-scheme-fix-fastcall.patch
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: readahead: initial method - expected read size - fix fastcall
From: Fengguang Wu <wfg@xxxxxxxxxxxxxxxx>
Remove 'fastcall' directive for function readahead_close().
It has drawn concerns from Andrew Morton. Now I have some benchmarks
on it, and proved it as a _false_ optimization.
The tests are simple runs of the following command over _cached_ dirs:
time find / > /dev/null
Table of summary(averages):
user sys cpu total
fastcall: 1.236 4.39 89% 6.2936
non-fastcall: 1.18 4.14166667 92% 5.75416667
stock: 1.25833333 4.14666667 93.3% 5.75866667
-----------
Detailed outputs:
readahead patched kernel with fastcall:
noglob find / > /dev/null 1.21s user 4.58s system 90% cpu 6.378 total
noglob find / > /dev/null 1.25s user 4.47s system 86% cpu 6.623 total
noglob find / > /dev/null 1.23s user 4.36s system 90% cpu 6.173 total
noglob find / > /dev/null 1.25s user 4.33s system 92% cpu 6.067 total
noglob find / > /dev/null 1.24s user 4.21s system 87% cpu 6.227 total
readahead patched kernel without fastcall:
noglob find / > /dev/null 1.21s user 4.46s system 95% cpu 5.962 total
noglob find / > /dev/null 1.26s user 4.58s system 94% cpu 6.142 total
noglob find / > /dev/null 1.10s user 3.80s system 86% cpu 5.661 total
noglob find / > /dev/null 1.13s user 3.98s system 95% cpu 5.355 total
noglob find / > /dev/null 1.18s user 4.00s system 89% cpu 5.805 total
noglob find / > /dev/null 1.22s user 4.03s system 93% cpu 5.600 total
stock kernel:
noglob find / > /dev/null 1.22s user 4.24s system 94% cpu 5.803 total
noglob find / > /dev/null 1.31s user 4.21s system 95% cpu 5.784 total
noglob find / > /dev/null 1.27s user 4.24s system 97% cpu 5.676 total
noglob find / > /dev/null 1.34s user 4.21s system 94% cpu 5.844 total
noglob find / > /dev/null 1.26s user 4.08s system 89% cpu 5.935 total
noglob find / > /dev/null 1.15s user 3.90s system 91% cpu 5.510 total
-----------
Similar regression has also been found by Voluspa <lista1@xxxxxxxxx>:
> "cd /usr ; time find . -type f -exec md5sum {} \;"
>
> 2.6.17-rc5 ------- 2.6.17-rc5-ar
>
> real 21m21.009s -- 21m37.663s
> user 3m20.784s -- 3m20.701s
> sys 6m34.261s -- 6m41.735s
Signed-off-by: Wu Fengguang <wfg@xxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
include/linux/mm.h | 2 +-
mm/readahead.c | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)
diff -puN include/linux/mm.h~readahead-call-scheme-fix-fastcall include/linux/mm.h
--- devel/include/linux/mm.h~readahead-call-scheme-fix-fastcall 2006-06-04 02:05:20.000000000 -0700
+++ devel-akpm/include/linux/mm.h 2006-06-04 02:05:20.000000000 -0700
@@ -991,7 +991,7 @@ unsigned long page_cache_readahead(struc
void handle_ra_miss(struct address_space *mapping,
struct file_ra_state *ra, pgoff_t offset);
unsigned long max_sane_readahead(unsigned long nr);
-void fastcall readahead_close(struct file *file);
+void readahead_close(struct file *file);
unsigned long
page_cache_readahead_adaptive(struct address_space *mapping,
struct file_ra_state *ra, struct file *filp,
diff -puN mm/readahead.c~readahead-call-scheme-fix-fastcall mm/readahead.c
--- devel/mm/readahead.c~readahead-call-scheme-fix-fastcall 2006-06-04 02:05:20.000000000 -0700
+++ devel-akpm/mm/readahead.c 2006-06-04 02:05:20.000000000 -0700
@@ -1845,7 +1845,7 @@ void fastcall readahead_cache_hit(struct
* The resulted `ra_expect_bytes' answers the question of:
* How many pages are expected to be read on start-of-file?
*/
-void fastcall readahead_close(struct file *file)
+void readahead_close(struct file *file)
{
struct inode *inode = file->f_dentry->d_inode;
struct address_space *mapping = inode->i_mapping;
_
Patches currently in -mm which might be from wfg@xxxxxxxxxxxxxxxx are
readahead-kconfig-options.patch
radixtree-introduce-radix_tree_scan_hole.patch
mm-introduce-probe_page.patch
mm-introduce-pg_readahead.patch
readahead-add-look-ahead-support-to-__do_page_cache_readahead.patch
readahead-delay-page-release-in-do_generic_mapping_read.patch
readahead-insert-cond_resched-calls.patch
readahead-minmax_ra_pages.patch
readahead-events-accounting.patch
readahead-rescue_pages.patch
readahead-sysctl-parameters.patch
readahead-sysctl-parameters-fix.patch
readahead-min-max-sizes.patch
readahead-state-based-method-aging-accounting.patch
readahead-state-based-method-routines.patch
readahead-state-based-method.patch
readahead-state-based-method-readahead-state-based-method-stand-alone-size-limit-code.patch
readahead-context-based-method.patch
readahead-context-based-method-apply-stream_shift-size-limits-to-contexta-method.patch
readahead-context-based-method-fix-remain-counting.patch
readahead-initial-method-guiding-sizes.patch
readahead-initial-method-thrashing-guard-size.patch
readahead-initial-method-expected-read-size.patch
readahead-initial-method-user-recommended-size.patch
readahead-initial-method.patch
readahead-backward-prefetching-method.patch
readahead-backward-prefetching-method-add-use-case-comment.patch
readahead-seeking-reads-method.patch
readahead-thrashing-recovery-method.patch
readahead-call-scheme.patch
readahead-call-scheme-fix-fastcall.patch
readahead-laptop-mode.patch
readahead-loop-case.patch
readahead-nfsd-case.patch
readahead-turn-on-by-default.patch
readahead-debug-radix-tree-new-functions.patch
readahead-debug-traces-showing-accessed-file-names.patch
readahead-debug-traces-showing-read-patterns.patch
-
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