grep with --extended-regexp much slower on Ubuntu 16.04

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grep with --extended-regexp much slower on Ubuntu 16.04

Brian Bird
I've noticed Ubuntu 16.04LTS seems to run greps with "-extended-regexp" much slower than Ubuntu 14.04LTS. I can reproduce this on the same hardware simply by re-installing with the relevant operating system.

Eg. On Ubuntu 14.04
# openssl rand -out /tmp/random.txt -base64 100000000; time grep --extended-regexp "[0-9]{10}$" /tmp/random.txt
real    0m0.513s
user    0m0.474s
sys     0m0.036s

On Ubuntu 16.04:
# openssl rand -out /tmp/random.txt -base64 100000000; time grep --extended-regexp "[0-9]{10}$" /tmp/random.txt

real    0m20.619s
user    0m20.587s
sys     0m0.028s

Q. Can anyone try the above commands and verify if they have similar problems?
Q. Can anyone suggest anything that might cause this?

Any pointers appreciated!
Thanks


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Re: grep with --extended-regexp much slower on Ubuntu 16.04

Duane Whitty
On 18-02-08 12:42 PM, Brian Bird wrote:

> I've noticed Ubuntu 16.04LTS seems to run greps with "-extended-regexp" much slower than Ubuntu 14.04LTS. I can reproduce this on the same hardware simply by re-installing with the relevant operating system.
>
> Eg. On Ubuntu 14.04
> # openssl rand -out /tmp/random.txt -base64 100000000; time grep --extended-regexp "[0-9]{10}$" /tmp/random.txt
> real    0m0.513s
> user    0m0.474s
> sys     0m0.036s
>
> On Ubuntu 16.04:
> # openssl rand -out /tmp/random.txt -base64 100000000; time grep --extended-regexp "[0-9]{10}$" /tmp/random.txt
>
> real    0m20.619s
> user    0m20.587s
> sys     0m0.028s
>
> Q. Can anyone try the above commands and verify if they have similar problems?
> Q. Can anyone suggest anything that might cause this?
>
> Any pointers appreciated!
> Thanks
>
>
For testing purposes I'd recommend generating the random text ahead of
time and thereby having the same input for the test on both platforms.

Best Regards,
Duane

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Re: grep with --extended-regexp much slower on Ubuntu 16.04

Karl Auer
In reply to this post by Brian Bird
On Thu, 2018-02-08 at 16:42 +0000, Brian Bird wrote:
> Eg. On Ubuntu 14.04
> # openssl rand -out /tmp/random.txt -base64 100000000; time grep --
> extended-regexp "[0-9]{10}$" /tmp/random.txt

It's possible that the generation of random data is taking longer on
one than the other. For this sort of test, you want to make sure that
the test is using the same data on both systems. Pre-generate those
chunk of random data and use the same chunks on both systems.

Regards, K.

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Re: grep with --extended-regexp much slower on Ubuntu 16.04

Karl Auer
In reply to this post by Duane Whitty
On Thu, 2018-02-08 at 16:31 -0400, Duane Whitty wrote:
> On 18-02-08 12:42 PM, Brian Bird wrote:
> > I've noticed Ubuntu 16.04LTS seems to run greps with "-extended-
> > regexp" much slower than Ubuntu 14.04LTS. I can reproduce this on
> > the same hardware simply by re-installing with the relevant
> > operating system.
> For testing purposes I'd recommend generating the random text ahead
> of time and thereby having the same input for the test on both
> platforms.

Ah. Oops. Yes, What he said :-)

Regards, K.

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Re: grep with --extended-regexp much slower on Ubuntu 16.04

Duane Whitty
In reply to this post by Karl Auer
On 18-02-08 05:03 PM, Karl Auer wrote:

> On Thu, 2018-02-08 at 16:42 +0000, Brian Bird wrote:
>> Eg. On Ubuntu 14.04
>> # openssl rand -out /tmp/random.txt -base64 100000000; time grep --
>> extended-regexp "[0-9]{10}$" /tmp/random.txt
>
> It's possible that the generation of random data is taking longer on
> one than the other. For this sort of test, you want to make sure that
> the test is using the same data on both systems. Pre-generate those
> chunk of random data and use the same chunks on both systems.
>
> Regards, K.
>
The time to generate the data is not the problem as the timer is not
being started until after the file has been created.  However, because
the data is random, the work required to do the matching could be
drastically different.

All of the above is assuming that the load is the same on both systems,
which may not be true.

Best Regards,
Duane

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Re: grep with --extended-regexp much slower on Ubuntu 16.04

Duane Whitty
In reply to this post by Brian Bird
On 18-02-08 12:42 PM, Brian Bird wrote:

> I've noticed Ubuntu 16.04LTS seems to run greps with "-extended-regexp" much slower than Ubuntu 14.04LTS. I can reproduce this on the same hardware simply by re-installing with the relevant operating system.
>
> Eg. On Ubuntu 14.04
> # openssl rand -out /tmp/random.txt -base64 100000000; time grep --extended-regexp "[0-9]{10}$" /tmp/random.txt
> real    0m0.513s
> user    0m0.474s
> sys     0m0.036s
>
> On Ubuntu 16.04:
> # openssl rand -out /tmp/random.txt -base64 100000000; time grep --extended-regexp "[0-9]{10}$" /tmp/random.txt
>
> real    0m20.619s
> user    0m20.587s
> sys     0m0.028s
>
> Q. Can anyone try the above commands and verify if they have similar problems?
> Q. Can anyone suggest anything that might cause this?
>
> Any pointers appreciated!
> Thanks
>
> One of my first questions should have been what kind of OS installation
are you doing, e.g., minimal server install, full blown X with desktop
environment, etc?  I believe to really get solid test results you need
to do a bare minimum install of the OS and preferably be in maintenance
mode before running the test.  To state the obvious, serious testing can
get complicated because it can be difficult to get rid of outside
influences.

Best Regards,
Duane

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Re: grep with --extended-regexp much slower on Ubuntu 16.04

Ralf Mardorf-2
On my Arch Linux install it doesn't make a difference if running
your grep line with LC_ALL=en_US.utf8 or LC_ALL=C on dash or bash,
with equal as well as different generated random.txt files, the result
is always

real 0m0.4[...]s
user 0m0.3[...]s
sys 0m0.0[...]s

so as already pointed out by other, running on the same hardware, there
still might be a difference regarding the load. Perhaps "top" shows a
fishy process taking too much CPU and/or RAM.


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RE: grep with --extended-regexp much slower on Ubuntu 16.04

Brian Bird
In reply to this post by Duane Whitty
Thanks for the various suggestions. Some things to note:

The timings are consistently slower no matter what version of random.txt is used. The example I gave was to make it as easy as possible for anyone to test on any machine, but the problem exists even if "random.txt" is the same in all cases.
The slower time only relates to the grep itself, not the generation of the random.txt file
This happens on a fresh install of a desktop version of Ubuntu 16.04 with no other software installed other than the default settings. It also happens on a minimal server install (with the only extra packages being things like sshd)
This happens when I reinstall 14.04 and 16.04 on the same hardware (I've tried other hardware too - same problem). However, even if the hardware causes some variation something this simple should not be an order of magnitude different in the timing.
The load on the machines is as low as possible when running these tests.  Some variation is caused by a variation in CPU or disk load, but it is consistently a *lot* slower.
I tried single user mode - same effect.
I tried different settings for LC_ALL but it had no effect. Both installations are defaulting to " en_GB"

I've also noticed that if --perl-regexp is used instead of --extended-regexp on Ubuntu 16.04 this is ~10 times faster (but not on Ubuntu 14.04). So the problem only exists with --extended-regexp

Some background - I'm looking into this because after upgrading to Ubuntu 16.04LTS server some other software I use is slower by ~40%. This particular issue is one part of it that appears to be contributing a significant portion of the slowdown.

Since I can reproduce this consistently I would like to know if anyone else can/can't reproduce it on Ubuntu 16.04LTS? As mentioned above, the example command I've given is to make it as easy as possible to test it rather than to be 100% consistent regarding the timing. But since the difference is so huge it doesn't matter if there is a little variance in the time to run the grep.


Eg. some abbreviated output with the same file:
Ubuntu 14:
09:29:12 up 19:59,  1 user,  load average: 0.01, 0.10, 0.09
time grep --extended-regexp "[0-9]{10}$" /tmp/random.txt
real    0m0.599s
# time grep --extended-regexp "[0-9]{10}$" /tmp/random.txt
real    0m0.607s
# time grep --extended-regexp "[0-9]{10}$" /tmp/random.txt
real    0m0.600s
09:29:20 up 19:59,  1 user,  load average: 0.01, 0.10, 0.09


But on Ubuntu 16:
09:31:42 up 21:22,  2 users,  load average: 0.10, 0.12, 0.09
# time grep --extended-regexp "[0-9]{10}$" /tmp/random.txt
real    0m5.585s
# time grep --extended-regexp "[0-9]{10}$" /tmp/random.txt
real    0m5.787s
# time grep --extended-regexp "[0-9]{10}$" /tmp/random.txt
real    0m5.648s
# time grep --perl-regexp "[0-9]{10}$" /tmp/random.txt
real    0m0.465s
09:34:16 up 21:25,  2 users,  load average: 0.16, 0.11, 0.09



-----Original Message-----
From: ubuntu-users [mailto:[hidden email]] On Behalf Of Duane Whitty
Sent: 08 February 2018 21:39
To: [hidden email]
Cc: [hidden email]
Subject: Re: grep with --extended-regexp much slower on Ubuntu 16.04

On 18-02-08 12:42 PM, Brian Bird wrote:

> I've noticed Ubuntu 16.04LTS seems to run greps with "-extended-regexp" much slower than Ubuntu 14.04LTS. I can reproduce this on the same hardware simply by re-installing with the relevant operating system.
>
> Eg. On Ubuntu 14.04
> # openssl rand -out /tmp/random.txt -base64 100000000; time grep --extended-regexp "[0-9]{10}$" /tmp/random.txt
> real    0m0.513s
> user    0m0.474s
> sys     0m0.036s
>
> On Ubuntu 16.04:
> # openssl rand -out /tmp/random.txt -base64 100000000; time grep
> --extended-regexp "[0-9]{10}$" /tmp/random.txt
>
> real    0m20.619s
> user    0m20.587s
> sys     0m0.028s
>
> Q. Can anyone try the above commands and verify if they have similar problems?
> Q. Can anyone suggest anything that might cause this?
>
> Any pointers appreciated!
> Thanks
>
> One of my first questions should have been what kind of OS
> installation
are you doing, e.g., minimal server install, full blown X with desktop environment, etc?  I believe to really get solid test results you need to do a bare minimum install of the OS and preferably be in maintenance mode before running the test.  To state the obvious, serious testing can get complicated because it can be difficult to get rid of outside influences.

Best Regards,
Duane

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Re: grep with --extended-regexp much slower on Ubuntu 16.04

Ralf Mardorf-2
On Fri, 9 Feb 2018 09:42:44 +0000, Brian Bird wrote:
>Since I can reproduce this consistently I would like to know if anyone
>else can/can't reproduce it on Ubuntu 16.04LTS?

Hi,

I can confirm that this at least happens when booting Ubuntu 16.04.3 LTS
from my Arch Linux install, in a systemd-nspawn container. It does even
happen, when running it in a systemd-nspawn container, if the boot option
isn't used, but if grep is run as user. Something is fishy, see [1].

Regards,
Ralf

[1]
[root@archlinux rocketmouse]# uname -a
Linux archlinux 4.14.15-rt13-1-rt-securityink #1 SMP PREEMPT RT Fri Feb 9 07:39:16 CET 2018 x86_64 GNU/Linux
[root@archlinux rocketmouse]# lsb_release -r
Release: rolling
[root@archlinux rocketmouse]# systemd-nspawn -bqD /mnt/moonstudio
[snip]
[weremouse@moonstudio ~]$ lsb_release -r
Release: 16.04
[weremouse@moonstudio ~]$ openssl rand -out /tmp/random.txt -base64 100000000
[weremouse@moonstudio ~]$ time grep --extended-regexp "[0-9]{10}$" /tmp/random.txt

real 0m13.041s
user 0m12.999s
sys 0m0.037s
[weremouse@moonstudio ~]$ time grep --extended-regexp "[0-9]{10}$" /tmp/random.txt

real 0m13.005s
user 0m12.989s
sys 0m0.011s
[weremouse@moonstudio ~]$ shutdown -h now
[snip]
[root@archlinux rocketmouse]# systemd-nspawn -qD /mnt/moonstudio
[root@moonstudio ~]# openssl rand -out /tmp/random.txt -base64 100000000
[root@moonstudio ~]# time grep --extended-regexp "[0-9]{10}$" /tmp/random.txt

real 0m0.539s
user 0m0.478s
sys 0m0.061s
[root@moonstudio ~]# time grep --extended-regexp "[0-9]{10}$" /tmp/random.txt

real 0m0.533s
user 0m0.512s
sys 0m0.021s
[root@moonstudio ~]# logout
[root@archlinux rocketmouse]# systemd-nspawn --help | grep boot
  -b --boot                 Boot up full system (i.e. invoke init)
[root@archlinux rocketmouse]# systemd-nspawn -qD /mnt/moonstudio
[root@moonstudio ~]# sudo -iu weremouse
[weremouse@moonstudio ~]$ openssl rand -out /tmp/random.txt -base64 100000000
[weremouse@moonstudio ~]$ time grep --extended-regexp "[0-9]{10}$" /tmp/random.txt

real 0m13.084s
user 0m13.038s
sys 0m0.041s
[weremouse@moonstudio ~]$ time grep --extended-regexp "[0-9]{10}$" /tmp/random.txt

real 0m13.059s
user 0m13.031s
sys 0m0.023s
[weremouse@moonstudio ~]$ logout
[root@moonstudio ~]# logout


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Re: grep with --extended-regexp much slower on Ubuntu 16.04

Ralf Mardorf-2
On Fri, 9 Feb 2018 19:35:52 +0100, Ralf Mardorf wrote:

>On Fri, 9 Feb 2018 09:42:44 +0000, Brian Bird wrote:
>>Since I can reproduce this consistently I would like to know if anyone
>>else can/can't reproduce it on Ubuntu 16.04LTS?  
>
>Hi,
>
>I can confirm that this at least happens when booting Ubuntu 16.04.3
>LTS from my Arch Linux install, in a systemd-nspawn container. It does
>even happen, when running it in a systemd-nspawn container, if the
>boot option isn't used, but if grep is run as user. Something is
>fishy, see [1].
>
>Regards,
>Ralf
>
>[1]
>[root@archlinux rocketmouse]# uname -a
>Linux archlinux 4.14.15-rt13-1-rt-securityink #1 SMP PREEMPT RT Fri
>Feb 9 07:39:16 CET 2018 x86_64 GNU/Linux [root@archlinux rocketmouse]#
>lsb_release -r Release: rolling
>[root@archlinux rocketmouse]# systemd-nspawn -bqD /mnt/moonstudio
>[snip]
>[weremouse@moonstudio ~]$ lsb_release -r
>Release: 16.04
>[weremouse@moonstudio ~]$ openssl rand -out /tmp/random.txt -base64
>100000000 [weremouse@moonstudio ~]$ time grep --extended-regexp
>"[0-9]{10}$" /tmp/random.txt
>
>real 0m13.041s
>user 0m12.999s
>sys 0m0.037s
>[weremouse@moonstudio ~]$ time grep --extended-regexp
>"[0-9]{10}$" /tmp/random.txt
>
>real 0m13.005s
>user 0m12.989s
>sys 0m0.011s
>[weremouse@moonstudio ~]$ shutdown -h now
>[snip]
>[root@archlinux rocketmouse]# systemd-nspawn -qD /mnt/moonstudio
>[root@moonstudio ~]# openssl rand -out /tmp/random.txt -base64
>100000000 [root@moonstudio ~]# time grep --extended-regexp
>"[0-9]{10}$" /tmp/random.txt
>
>real 0m0.539s
>user 0m0.478s
>sys 0m0.061s
>[root@moonstudio ~]# time grep --extended-regexp
>"[0-9]{10}$" /tmp/random.txt
>
>real 0m0.533s
>user 0m0.512s
>sys 0m0.021s
>[root@moonstudio ~]# logout
>[root@archlinux rocketmouse]# systemd-nspawn --help | grep boot
>  -b --boot                 Boot up full system (i.e. invoke init)
>[root@archlinux rocketmouse]# systemd-nspawn -qD /mnt/moonstudio
>[root@moonstudio ~]# sudo -iu weremouse
>[weremouse@moonstudio ~]$ openssl rand -out /tmp/random.txt -base64
>100000000 [weremouse@moonstudio ~]$ time grep --extended-regexp
>"[0-9]{10}$" /tmp/random.txt
>
>real 0m13.084s
>user 0m13.038s
>sys 0m0.041s
>[weremouse@moonstudio ~]$ time grep --extended-regexp
>"[0-9]{10}$" /tmp/random.txt
>
>real 0m13.059s
>user 0m13.031s
>sys 0m0.023s
>[weremouse@moonstudio ~]$ logout
>[root@moonstudio ~]# logout

FWIW it's seemingly not related to page-table isolation. I booted
Arch Linux from the below "LABEL Securityink" and not from the
"LABEL Securityink_nopti", however, 16.04 useres could test, if booting
with "nokaiser" makes a differences. Arch's grep doesn't suffer from the
performance issue. FWIW Arch's microcode is revision 0x23, while
Ubuntu's is revision 0x22, but this shouldn't matter, since I run Ubuntu
in a container.

[rocketmouse@archlinux ~]$ openssl rand -out /tmp/random.txt -base64 100000000
[rocketmouse@archlinux ~]$ time grep --extended-regexp "[0-9]{10}$" /tmp/random.txt

real 0m0.419s
user 0m0.375s
sys 0m0.043s
[rocketmouse@archlinux ~]$ cat /boot/syslinux/syslinux.cfg
# http://syslinux.zytor.com/wiki/index.php/Doc/menu

PROMPT 0
TIMEOUT 600
UI menu.c32
MENU HIDDEN
MENU CLEAR
MENU COLOR screen      0;30;40
MENU COLOR border      0;30;40
MENU COLOR title       1;37;44
MENU COLOR unsel       0;37;40
MENU COLOR hotkey      1;37;40
MENU COLOR hotsel      7;37;40
MENU COLOR sel         7;37;40
MENU COLOR disabled    1;37;40
MENU COLOR scrollbar   0;30;40
MENU COLOR tabmsg      0;30;40
MENU COLOR cmdmark     0;31;40
MENU COLOR cmdline     0;37;40
MENU COLOR timeout_msg 0;37;40
MENU COLOR timeout     1;37;40

# Used hotkeys: ^8 ^A ^C ^e ^H ^i ^k ^M ^n ^P ^Q ^R ^S ^t ^V
DEFAULT Securityink

MENU TITLE HAL 9000
LABEL Toolbox
    MENU LABEL Toolbox
    MENU DISABLE
MENU SEPARATOR


LABEL Hardware
    MENU LABEL ^Hardware Detection
    COM32 hdt.c32

LABEL Memtest
    MENU LABEL Memtest^86+
    LINUX /.boot/ubuntu_moonstudio/boot/memtest86+.bin

LABEL Reset
    MENU LABEL R^eset
    COM32 reboot.c32


MENU SEPARATOR
MENU SEPARATOR
LABEL Arch Menu
    MENU LABEL Arch Linux
    MENU DISABLE
MENU SEPARATOR


LABEL Threadirqs
    MENU LABEL Arch Linux ^threadirqs
    LINUX ../vmlinuz-linux
    APPEND root=LABEL=archlinux ro threadirqs
    INITRD ../intel-ucode.img,../initramfs-linux.img

LABEL Threadirqs_nopti
    MENU LABEL Arch Linux threadirqs ^nopti
    LINUX ../vmlinuz-linux
    APPEND root=LABEL=archlinux ro threadirqs nopti
    INITRD ../intel-ucode.img,../initramfs-linux.img

LABEL Securityink
    MENU LABEL Arch Linux Rt ^Securityink
    LINUX ../vmlinuz-linux-rt-securityink
    APPEND root=LABEL=archlinux ro
    INITRD ../intel-ucode.img,../initramfs-linux-rt-securityink.img

LABEL Securityink_nopti
    MENU LABEL Arch Linux Rt Securityink nopt^i
    LINUX ../vmlinuz-linux-rt-securityink
    APPEND root=LABEL=archlinux ro nopti
    INITRD ../intel-ucode.img,../initramfs-linux-rt-securityink.img

LABEL Pussytoes
    MENU LABEL Arch Linux Rt ^Pussytoes
    LINUX ../vmlinuz-linux-rt-pussytoes
    APPEND root=LABEL=archlinux ro
    INITRD ../intel-ucode.img,../initramfs-linux-rt-pussytoes.img

LABEL Cornflower
    MENU LABEL Arch Linux Rt ^Cornflower
    LINUX ../vmlinuz-linux-rt-cornflower
    APPEND root=LABEL=archlinux ro
    INITRD ../intel-ucode.img,../initramfs-linux-rt-cornflower.img

LABEL Rt
    MENU LABEL Arch Linux ^Rt
    LINUX ../vmlinuz-linux-rt
    APPEND root=LABEL=archlinux ro
    INITRD ../intel-ucode.img,../initramfs-linux-rt.img

LABEL Arch
    MENU LABEL ^Arch Linux
    LINUX ../vmlinuz-linux
    APPEND root=LABEL=archlinux ro
    INITRD ../intel-ucode.img,../initramfs-linux.img


MENU SEPARATOR
MENU SEPARATOR
LABEL Other Menu
    MENU LABEL Other Linux
    MENU DISABLE
MENU SEPARATOR


LABEL Moonstudio
    MENU LABEL Ubuntu X ^Moon Studio lowlatency
    LINUX /.boot/ubuntu_moonstudio/boot/vmlinuz-lowlatency
    APPEND root=LABEL=moonstudio ro
    INITRD /.boot/ubuntu_moonstudio/boot/initrd.img-lowlatency

LABEL Nokaiser
    MENU LABEL Ubuntu X Moon Studio lowlatency no^kaiser
    LINUX /.boot/ubuntu_moonstudio/boot/vmlinuz-lowlatency
    APPEND root=LABEL=moonstudio ro nokaiser
    INITRD /.boot/ubuntu_moonstudio/boot/initrd.img-lowlatency

LABEL Light
    MENU LABEL Ubuntu ^Q LightScribe Rt
    LINUX /.boot/ubuntu_q/boot/vmlinuz-3.6.5-rt14
    APPEND root=LABEL=q ro nomodeset
    INITRD /.boot/ubuntu_q/boot/initrd.img-3.6.5-rt14

LABEL Suse
    MENU LABEL ^Vintage  SUSE 11.2   Rt
    LINUX /.boot/suse11.2/boot/vmlinuz-2.6.31.6-rt19
    APPEND root=LABEL=suse11.2
    INITRD /.boot/suse11.2/boot/initrd-2.6.31.6-rt19


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Re: grep with --extended-regexp much slower on Ubuntu 16.04

C de-Avillez-2
In reply to this post by Ralf Mardorf-2
On Fri, 9 Feb 2018 19:35:52 +0100
Ralf Mardorf <[hidden email]> wrote:

> On Fri, 9 Feb 2018 09:42:44 +0000, Brian Bird wrote:
> >Since I can reproduce this consistently I would like to know if
> >anyone else can/can't reproduce it on Ubuntu 16.04LTS?  
>
> Hi,
>
> I can confirm that this at least happens when booting Ubuntu 16.04.3
> LTS from my Arch Linux install, in a systemd-nspawn container. It
> does even happen, when running it in a systemd-nspawn container, if
> the boot option isn't used, but if grep is run as user. Something is
> fishy, see [1].

Perhaps (in fact, probably) related to bug 26193 on grep? Please see
the thread on this at [1]. The fix was included in grep 3.1.

Cheers,

..C..


[1] https://lists.gnu.org/archive/html/bug-grep/2017-03/msg00009.html

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Re: grep with --extended-regexp much slower on Ubuntu 16.04

Ralf Mardorf-2
On Fri, 9 Feb 2018 16:23:42 -0600, C de-Avillez wrote:
>Perhaps (in fact, probably) related to bug 26193 on grep? Please see
>the thread on this at [1]. The fix was included in grep 3.1.
>[1] https://lists.gnu.org/archive/html/bug-grep/2017-03/msg00009.html

Hi,

probably, but actually I didn't read it, at least any guess regarding
page-table islation likely is nonsense, maybe not only because the
booted kernel 4.14.15-rt13-1-rt-securityink might not include the patch
set [2], I confused 4.15 with 4.14.15.
                     ^^^       ^^^^^^        

[2]
On Fri, 9 Feb 2018 19:52:41 +0100, Ralf Mardorf wrote:
>LABEL Securityink_nopti
>    MENU LABEL Arch Linux Rt Securityink nopt^i
>    LINUX ../vmlinuz-linux-rt-securityink
>    APPEND root=LABEL=archlinux ro nopti
>    INITRD ../intel-ucode.img,../initramfs-linux-rt-securityink.img

Now commented out in my bootloader's config:

# "KPTI was merged into Linux kernel version 4.15,[snip] and backported to Linux kernels 4.14.11, 4.9.75, 4.4.110."
# - https://en.wikipedia.org/wiki/Kernel_page-table_isolation
#LABEL Securityink_nopti
#    MENU LABEL Arch Linux Rt Securityink nopt^i
#    LINUX ../vmlinuz-linux-rt-securityink
#    APPEND root=LABEL=archlinux ro nopti
#    INITRD ../intel-ucode.img,../initramfs-linux-rt-securityink.img

--
$ pacman -Q linux{,-rt-securityink,-rt,-rt-pussytoes,-rt-cornflower}
linux 4.15.2-2
linux-rt-securityink 4.14.18_rt15-1
linux-rt 4.14.12_rt10-1
linux-rt-pussytoes 4.14.8_rt9-2
linux-rt-cornflower 4.11.12_rt16-1


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RE: grep with --extended-regexp much slower on Ubuntu 16.04

Brian Bird
On Fri, 9 Feb 2018 16:23:42 -0600, C de-Avillez wrote:
>Perhaps (in fact, probably) related to bug 26193 on grep? Please see
>the thread on this at [1]. The fix was included in grep 3.1.
>[1] https://lists.gnu.org/archive/html/bug-grep/2017-03/msg00009.html

I just tried grep 3.1 downloaded from the artful repository and that seems to fix it:

# dpkg -i /tmp/grep_3.1-2_amd64.deb
# openssl rand -out /tmp/random.txt -base64 100000000; time grep --extended-regexp "[0-9]{10}$" /tmp/random.txt
real    0m0.413s
user    0m0.368s
sys     0m0.040s


Strange Ubuntu have left such a bug in a LTS release. At first glance it doesn't look like this causes any obvious compatibility problems, so I may stick with it. Thanks for all your help/suggestions!

Brian

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