The patch titled
io-accounting: remove current io accounting
has been added to the -mm tree. Its filename is
io-accounting-remove-current-io-accounting.patch
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: io-accounting: remove current io accounting
From: Andrew Morton <akpm@xxxxxxxx>
The present per-task IO accounting is unusable. It simply counts the number
of bytes passed into read() and write(). So if a process reads 1MB from an
already-cached file, it is accused of having performed 1MB of I/O, which is
hopelessly wrong.
This patchset removes the old IO accounting and replaces it with new
accounting which tries to be more accurate. We account for three things:
reads:
attempt to count the number of bytes which this process really did cause
to be fetched from the storage layer
writes:
attempt to count the number of bytes which this process caused to be sent
to the storage layer.
The big inaccuracy here is truncate. If a process writes 1MB to a file
and then deletes the file, it will in fact perform no writeout. But it will
have been accounted as having caused 1MB of write.
So...
cancelled_writes:
account the number of bytes which this process caused to not happen, by
truncating pagecache.
We _could_ just subtract this from the process's `write' accounting. But
that means that some processes would be reported to have done negative
amounts of write IO, which is silly.
So we just report the raw number and punt this decision up to userspace.
There are some open questions:
- What the heck's going on with userspace? The example getdelays.c appears
to exercise no more than a fraction of the taskstats interface. How do I
get at my numbers?
- Missing accounting of filesystem metadata reads
- Filesystems which implement private a_ops.readpages might need work.
- What to do about things like NFS? It will probably presently account
_some_ IO, but it'll be wrong.
This patch:
Remove the old IO accounting, but leave the fields in the taskstats structure
in-place, but zeroed.
Cc: Jay Lan <jlan@xxxxxxx>
Cc: Shailabh Nagar <nagar@xxxxxxxxxxxxxx>
Cc: Balbir Singh <balbir@xxxxxxxxxx>
Cc: Chris Sturtivant <csturtiv@xxxxxxx>
Cc: Tony Ernst <tee@xxxxxxx>
Cc: Guillaume Thouvenin <guillaume.thouvenin@xxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
fs/read_write.c | 18 ++----------------
include/linux/sched.h | 4 ++--
kernel/fork.c | 2 --
kernel/tsacct.c | 4 ++--
4 files changed, 6 insertions(+), 22 deletions(-)
diff -puN fs/read_write.c~io-accounting-remove-current-io-accounting fs/read_write.c
--- a/fs/read_write.c~io-accounting-remove-current-io-accounting
+++ a/fs/read_write.c
@@ -272,10 +272,8 @@ ssize_t vfs_read(struct file *file, char
ret = file->f_op->read(file, buf, count, pos);
else
ret = do_sync_read(file, buf, count, pos);
- if (ret > 0) {
+ if (ret > 0)
fsnotify_access(file->f_dentry);
- current->rchar += ret;
- }
current->syscr++;
}
}
@@ -330,10 +328,8 @@ ssize_t vfs_write(struct file *file, con
ret = file->f_op->write(file, buf, count, pos);
else
ret = do_sync_write(file, buf, count, pos);
- if (ret > 0) {
+ if (ret > 0)
fsnotify_modify(file->f_dentry);
- current->wchar += ret;
- }
current->syscw++;
}
}
@@ -675,9 +671,6 @@ sys_readv(unsigned long fd, const struct
file_pos_write(file, pos);
fput_light(file, fput_needed);
}
-
- if (ret > 0)
- current->rchar += ret;
current->syscr++;
return ret;
}
@@ -696,9 +689,6 @@ sys_writev(unsigned long fd, const struc
file_pos_write(file, pos);
fput_light(file, fput_needed);
}
-
- if (ret > 0)
- current->wchar += ret;
current->syscw++;
return ret;
}
@@ -780,10 +770,6 @@ static ssize_t do_sendfile(int out_fd, i
retval = in_file->f_op->sendfile(in_file, ppos, count, file_send_actor, out_file);
- if (retval > 0) {
- current->rchar += retval;
- current->wchar += retval;
- }
current->syscr++;
current->syscw++;
diff -puN include/linux/sched.h~io-accounting-remove-current-io-accounting include/linux/sched.h
--- a/include/linux/sched.h~io-accounting-remove-current-io-accounting
+++ a/include/linux/sched.h
@@ -1002,8 +1002,8 @@ struct task_struct {
* to a stack based synchronous wait) if its doing sync IO.
*/
wait_queue_t *io_wait;
-/* i/o counters(bytes read/written, #syscalls */
- u64 rchar, wchar, syscr, syscw;
+ u64 syscr; /* number of read syscalls */
+ u64 syscw; /* number of write syscalls */
#if defined(CONFIG_TASK_XACCT)
u64 acct_rss_mem1; /* accumulated rss usage */
u64 acct_vm_mem1; /* accumulated virtual memory usage */
diff -puN kernel/fork.c~io-accounting-remove-current-io-accounting kernel/fork.c
--- a/kernel/fork.c~io-accounting-remove-current-io-accounting
+++ a/kernel/fork.c
@@ -1051,8 +1051,6 @@ static struct task_struct *copy_process(
p->utime = cputime_zero;
p->stime = cputime_zero;
p->sched_time = 0;
- p->rchar = 0; /* I/O counter: bytes read */
- p->wchar = 0; /* I/O counter: bytes written */
p->syscr = 0; /* I/O counter: read syscalls */
p->syscw = 0; /* I/O counter: write syscalls */
acct_clear_integrals(p);
diff -puN kernel/tsacct.c~io-accounting-remove-current-io-accounting kernel/tsacct.c
--- a/kernel/tsacct.c~io-accounting-remove-current-io-accounting
+++ a/kernel/tsacct.c
@@ -92,8 +92,8 @@ void xacct_add_tsk(struct taskstats *sta
stats->hiwater_vm = mm->hiwater_vm * PAGE_SIZE / KB;
mmput(mm);
}
- stats->read_char = p->rchar;
- stats->write_char = p->wchar;
+ stats->read_char = 0;
+ stats->write_char = 0;
stats->read_syscalls = p->syscr;
stats->write_syscalls = p->syscw;
}
_
Patches currently in -mm which might be from akpm@xxxxxxxx are
origin.patch
git-acpi.patch
video-sysfs-support-take-2-add-dev-argument-for-backlight_device_register.patch
acpi-asus-s3-resume-fix.patch
sony_apci-resume.patch
video-sysfs-support-take-2-add-dev-argument-for-backlight_device_register-sony_acpi-fix.patch
git-cpufreq-prep.patch
git-cpufreq.patch
git-powerpc.patch
fix-gregkh-driver-sound-device.patch
git-dvb.patch
git-dvb-fixup.patch
git-gfs2-nmw.patch
git-ia64.patch
git-input.patch
git-input-fixup.patch
git-libata-all.patch
via-pata-controller-xfer-fixes-fix.patch
git-mtd.patch
git-netdev-all.patch
git-netdev-all-fixup.patch
libphy-dont-do-that.patch
update-smc91x-driver-with-arm-versatile-board-info.patch
drivers-net-ns83820c-add-paramter-to-disable-auto.patch
git-net.patch
net-uninline-skb_put.patch
ioat-warning-fix.patch
tidy-gregkh-pci-pci-check-szhi-when-sz-is-0-when-64-bit-iomem-bigger-than-4g.patch
fix-gregkh-pci-pci-check-szhi-when-sz-is-0-when-64-bit-iomem-bigger-than-4g.patch
fix-2-gregkh-pci-pci-check-szhi-when-sz-is-0-when-64-bit-iomem-bigger-than-4g.patch
git-scsi-misc.patch
drivers-scsi-mca_53c9xc-save_flags-cli-removal.patch
nokia-e70-is-an-unusual-device.patch
git-watchdog.patch
pre-x86_64-mm-i386-reloc-abssym.patch
post-x86_64-mm-i386-reloc-abssym.patch
touchkit-ps-2-touchscreen-driver.patch
get-rid-of-zone_table.patch
new-scheme-to-preempt-swap-token-tidy.patch
balance_pdgat-cleanup.patch
add-numa-node-information-to-struct-device-tidy.patch
node-aware-skb-allocation-fix-for-device-tree-changes.patch
radix-tree-rcu-lockless-readside.patch
acx1xx-wireless-driver.patch
security-introduce-file-caps-tweaks.patch
security-introduce-file-caps-warning-fix.patch
swsusp-add-resume_offset-command-line-parameter-rev-2.patch
add-include-linux-freezerh-and-move-definitions-from-ueagle-fix.patch
cciss-set-sector_size-to-2048-for-performance-tidy.patch
deprecate-smbfs-in-favour-of-cifs.patch
edac-new-opteron-athlon64-memory-controller-driver.patch
kbuild-dont-put-temp-files-in-the-source-tree.patch
lockdep-annotate-nfs-nfsd-in-kernel-sockets-tidy.patch
drivers-add-lcd-support-3-Kconfig-fix.patch
probe_kernel_address-needs-to-do-set_fs.patch
slab-use-probe_kernel_address.patch
lockdep-spin_lock_irqsave_nested-fix.patch
lockdep-spin_lock_irqsave_nested-fix-2.patch
aio-use-prepare_to_wait.patch
exar-quad-port-serial-fix.patch
vfs_getattr-remove-dead-code.patch
ext3-uninline-large-functions.patch
ext4-uninline-large-functions.patch
uninline-module_put.patch
sleep-profiling-fixes.patch
sleep-profiling-fix.patch
debug-workqueue-locking-sanity-fix.patch
pcengines-wrap-led-support-fix.patch
driver-base-memoryc-remove-warnings-of.patch
remove-kernel-syscalls-x86_64-fix.patch
protect-ext2-ioctl-modifying-append_only-immutable-etc-with-i_mutex.patch
remove-hash_highmem.patch
elf-fix-kcore-note-size-calculation-fix.patch
reiserfs-add-missing-d-cache-flushing-tweak.patch
io-accounting-remove-current-io-accounting.patch
io-accounting-core-statistics.patch
clean-up-__set_page_dirty_nobuffers.patch
io-accounting-write-accounting.patch
io-accounting-write-cancel-accounting.patch
io-accounting-read-accounting.patch
io-accounting-direct-io.patch
io-accounting-report-in-procfs.patch
cleanup-taskstatsh.patch
io-accounting-via-taskstats.patch
getdelays-various-fixes.patch
ext2-reservations.patch
ext2-reservations-fix-42.patch
ext2-reservations-fix-ext2_new_blocks-type.patch
ext2-reservations-fix-ext2_new_block-type.patch
pktcdvd-bio-write-congestion-using-blk_congestion_wait-fix.patch
bug-test-1.patch
fsstack-introduce-fsstack_copy_attrinode_-tidy.patch
log2-implement-a-general-integer-log2-facility-in-the-kernel-fix.patch
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add-process_session-helper-routine-deprecate-old-field-tidy.patch
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fault-injection-capabilities-infrastructure-tidy.patch
fault-injection-capabilities-infrastructure-tweaks.patch
fault-injection-Kconfig-cleanup.patch
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make-kmem_cache_destroy-return-void-reiser4.patch
reiser4-hardirq-include-fix.patch
reiser4-run-truncate_inode_pages-in-reiser4_delete_inode.patch
reiser4-get_sb_dev-fix.patch
reiser4-vs-zoned-allocator.patch
reiser4-temp-fix.patch
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extend-notifier_call_chain-to-count-nr_calls-made.patch
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gtod-persistent-clock-support-i386.patch
updated-hrtimers-state-tracking.patch
updated-i386-convert-to-clock-event-devices.patch
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updated-gtod-mark-tsc-unusable-for-highres-timers.patch
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clocksource-small-cleanup-2-fix.patch
kevent_user_wait-retval-fix.patch
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