Skip to content

K
Kernel

openeuler / Kernel
1 年多 前同步成功

通知 8
Star 0
Fork 0
K
Kernel
切换分支/标签
  1. 11 2月, 2015 5 次提交
    • K
      rmap: drop support of non-linear mappings · 27ba0644
      由 Kirill A. Shutemov 提交于 
      We don't create non-linear mappings anymore.  Let's drop code which
handles them in rmap.
Signed-off-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      27ba0644
    • K
      mm: replace remap_file_pages() syscall with emulation · c8d78c18
      由 Kirill A. Shutemov 提交于 
      remap_file_pages(2) was invented to be able efficiently map parts of
huge file into limited 32-bit virtual address space such as in database
workloads.

Nonlinear mappings are pain to support and it seems there's no
legitimate use-cases nowadays since 64-bit systems are widely available.

Let's drop it and get rid of all these special-cased code.

The patch replaces the syscall with emulation which creates new VMA on
each remap_file_pages(), unless they it can be merged with an adjacent
one.

I didn't find *any* real code that uses remap_file_pages(2) to test
emulation impact on.  I've checked Debian code search and source of all
packages in ALT Linux.  No real users: libc wrappers, mentions in
strace, gdb, valgrind and this kind of stuff.

There are few basic tests in LTP for the syscall.  They work just fine
with emulation.

To test performance impact, I've written small test case which
demonstrate pretty much worst case scenario: map 4G shmfs file, write to
begin of every page pgoff of the page, remap pages in reverse order,
read every page.

The test creates 1 million of VMAs if emulation is in use, so I had to
set vm.max_map_count to 1100000 to avoid -ENOMEM.

Before:		23.3 ( +-  4.31% ) seconds
After:		43.9 ( +-  0.85% ) seconds
Slowdown:	1.88x

I believe we can live with that.

Test case:

        #define _GNU_SOURCE
        #include <assert.h>
        #include <stdlib.h>
        #include <stdio.h>
        #include <sys/mman.h>

        #define MB	(1024UL * 1024)
        #define SIZE	(4096 * MB)

        int main(int argc, char **argv)
        {
                unsigned long *p;
                long i, pass;

                for (pass = 0; pass < 10; pass++) {
                        p = mmap(NULL, SIZE, PROT_READ|PROT_WRITE,
                                        MAP_SHARED | MAP_ANONYMOUS, -1, 0);
                        if (p == MAP_FAILED) {
                                perror("mmap");
                                return -1;
                        }

                        for (i = 0; i < SIZE / 4096; i++)
                                p[i * 4096 / sizeof(*p)] = i;

                        for (i = 0; i < SIZE / 4096; i++) {
                                if (remap_file_pages(p + i * 4096 / sizeof(*p), 4096,
                                                0, (SIZE - 4096 * (i + 1)) >> 12, 0)) {
                                        perror("remap_file_pages");
                                        return -1;
                                }
                        }

                        for (i = SIZE / 4096 - 1; i >= 0; i--)
                                assert(p[i * 4096 / sizeof(*p)] == SIZE / 4096 - i - 1);

                        munmap(p, SIZE);
                }

                return 0;
        }

[akpm@linux-foundation.org: fix spello]
[sasha.levin@oracle.com: initialize populate before usage]
[sasha.levin@oracle.com: grab file ref to prevent race while mmaping]
Signed-off-by: N"Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Dave Jones <davej@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Armin Rigo <arigo@tunes.org>
Signed-off-by: NSasha Levin <sasha.levin@oracle.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      c8d78c18
    • D
      fsioctl.c: make generic_block_fiemap() signal-tolerant · 913e027c
      由 Dmitry Monakhov 提交于 
      __generic_block_fiemap may spin very long time for large sparse files.

Without this patch an unprivileged user may abuse system resources simply
by spawning a vast number of unkilable busyloops (works on ext2/ext3):

  truncate --size 1T test
  for ((i=0;i<1024;i++))
  do
         filefrag test > /dev/null &
  done
Signed-off-by: NDmitry Monakhov <dmonakhov@openvz.org>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      913e027c
    • A
      ocfs2: add a mount option journal_async_commit on ocfs2 filesystem · 1dfeb768
      由 alex chen 提交于 
      Add a mount option to support JBD2 feature:

JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT.  When this feature is opened, journal
commit block can be written to disk without waiting for descriptor blocks,
which can improve journal commit performance.  This option will enable
'journal_checksum' internally.

Using the fs_mark benchmark, using journal_async_commit shows a 50%
improvement, the files per second go up from 215.2 to 317.5.

test script:
fs_mark  -d  /mnt/ocfs2/  -s  10240  -n  1000

default:
FSUse%        Count         Size    Files/sec     App Overhead
     0         1000        10240        215.2            17878

with journal_async_commit option:
FSUse%        Count         Size    Files/sec     App Overhead
     0         1000        10240        317.5            17881
Signed-off-by: NAlex Chen <alex.chen@huawei.com>
Signed-off-by: NWeiwei Wang <wangww631@huawei.comm>
Reviewed-by: NJoseph Qi <joseph.qi@huawei.com>
Reviewed-by: NMark Fasheh <mfasheh@suse.de>
Cc: Joel Becker <jlbec@evilplan.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      1dfeb768
    • Z
      inotify: update documentation to reflect code changes · a5b2f95d
      由 Zhang Zhen 提交于 
      The inotify interface has changed a lot.  The user interface was too
old, and the kernel interface was removed by Eric Paris in commit:
2dfc1cae inotify: remove inotify in kernel interface.
Signed-off-by: NZhang Zhen <zhenzhang.zhang@huawei.com>
Cc: Wang Kai <morgan.wang@huawei.com>
Cc: Eric Paris <eparis@parisplace.org>
Cc: Robert Love <robert.w.love@intel.com>
Cc: John McCutchan <john@johnmccutchan.com>
Cc: Heinrich Schuchardt <xypron.glpk@gmx.de>
Acked-by: NJan Kara <jack@suse.cz>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      a5b2f95d
  3. 10 2月, 2015 1 次提交
  5. 08 2月, 2015 1 次提交
    • N
      tcp: helpers to mitigate ACK loops by rate-limiting out-of-window dupacks · 032ee423
      由 Neal Cardwell 提交于 
      Helpers for mitigating ACK loops by rate-limiting dupacks sent in
response to incoming out-of-window packets.

This patch includes:

- rate-limiting logic
- sysctl to control how often we allow dupacks to out-of-window packets
- SNMP counter for cases where we rate-limited our dupack sending

The rate-limiting logic in this patch decides to not send dupacks in
response to out-of-window segments if (a) they are SYNs or pure ACKs
and (b) the remote endpoint is sending them faster than the configured
rate limit.

We rate-limit our responses rather than blocking them entirely or
resetting the connection, because legitimate connections can rely on
dupacks in response to some out-of-window segments. For example, zero
window probes are typically sent with a sequence number that is below
the current window, and ZWPs thus expect to thus elicit a dupack in
response.

We allow dupacks in response to TCP segments with data, because these
may be spurious retransmissions for which the remote endpoint wants to
receive DSACKs. This is safe because segments with data can't
realistically be part of ACK loops, which by their nature consist of
each side sending pure/data-less ACKs to each other.

The dupack interval is controlled by a new sysctl knob,
tcp_invalid_ratelimit, given in milliseconds, in case an administrator
needs to dial this upward in the face of a high-rate DoS attack. The
name and units are chosen to be analogous to the existing analogous
knob for ICMP, icmp_ratelimit.

The default value for tcp_invalid_ratelimit is 500ms, which allows at
most one such dupack per 500ms. This is chosen to be 2x faster than
the 1-second minimum RTO interval allowed by RFC 6298 (section 2, rule
2.4). We allow the extra 2x factor because network delay variations
can cause packets sent at 1 second intervals to be compressed and
arrive much closer.
Reported-by: NAvery Fay <avery@mixpanel.com>
Signed-off-by: NNeal Cardwell <ncardwell@google.com>
Signed-off-by: NYuchung Cheng <ycheng@google.com>
Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      032ee423
  7. 07 2月, 2015 2 次提交
  9. 06 2月, 2015 2 次提交
  11. 05 2月, 2015 5 次提交
  13. 04 2月, 2015 4 次提交
  15. 03 2月, 2015 6 次提交
  17. 02 2月, 2015 1 次提交
  19. 31 1月, 2015 1 次提交
  21. 30 1月, 2015 12 次提交