Re: Sudden slowdown of ARM emulation in master

[Igor Mammedov <imammedo@redhat.com>]

On Wed, 26 Feb 2020 00:07:55 +0100
Niek Linnenbank <nieklinnenbank@gmail.com> wrote:

> Hello Igor and Paolo,

does following hack solves issue?

diff --git a/accel/tcg/translate-all.c b/accel/tcg/translate-all.c
index a08ab11f65..ab2448c5aa 100644
--- a/accel/tcg/translate-all.c
+++ b/accel/tcg/translate-all.c
@@ -944,7 +944,7 @@ static inline size_t size_code_gen_buffer(size_t tb_size)
         /* ??? If we relax the requirement that CONFIG_USER_ONLY use the
            static buffer, we could size this on RESERVED_VA, on the text
            segment size of the executable, or continue to use the default.  */
-        tb_size = (unsigned long)(ram_size / 4);
+        tb_size = MAX_CODE_GEN_BUFFER_SIZE;
 #endif
     }
     if (tb_size < MIN_CODE_GEN_BUFFER_SIZE) {


> 
> Just now I was working on some small fixes for the cubieboard machine and
> rebasing my Allwinner H3 branches.
> While doing some testing, I noticed that suddenly the machines were much
> slower than before.
> I only see this happening when I rebase to this commit:
>    ca6155c0f2bd39b4b4162533be401c98bd960820 ("Merge tag 'patchew/
> 20200219160953.13771-1-imammedo@redhat.com' of
> https://github.com/patchew-project/qemu into HEAD")
> 
> Also the avocado tests I'm running started to timeout:
> 
> + AVOCADO_ALLOW_LARGE_STORAGE=yes avocado --show=app,console run -t
> machine:cubieboard tests/acceptance/boot_linux_console.py
> ...
> (1/2)
> tests/acceptance/boot_linux_console.py:BootLinuxConsole.test_arm_cubieboard_initrd:
> |console: Uncompressing Linux... done, booting the kernel.
> |console: Booting Linux on physical CPU 0x0
> console: Linux version 4.20.7-sunxi (root@armbian.com) (gcc version 7.2.1
> 20171011 (Linaro GCC 7.2-2017.11)) #5.75 SMP Fri Feb 8 09:02:10 CET 2019
> console: CPU: ARMv7 Processor [410fc080] revision 0 (ARMv7), cr=50c5387d
> console: CPU: PIPT / VIPT nonaliasing data cache, VIPT nonaliasing
> instruction cache
> console: OF: fdt: Machine model: Cubietech Cubieboard
> ...
> INTERRUPTED: Test interrupted by SIGTERM\nRunner error occurred: Timeout
> reached\n
> Original status: ERROR\n{'name':
> '1-tests/acceptance/boot_linux_console.py:BootLinuxConsole.test_arm_cubieboard_initrd',
> 'logdir': '/home/me/avocado/job-results/job-2020-02-25T23.58-d43884...
> (90.41 s)
> ...
> console: random: crng init done
> /console: mount: mounting devtmpfs on /dev failed: Device or resource busy
> -console: EXT4-fs (sda): re-mounted. Opts:
> block_validity,barrier,user_xattr,acl
> /console: Starting logging: OK
> INTERRUPTED: Test interrupted by SIGTERM\nRunner error occurred: Timeout
> reached\nOriginal status: ERROR\n{'name':
> '2-tests/acceptance/boot_linux_console.py:BootLinuxConsole.test_arm_cubieboard_sata',
> 'logdir': '/home/fox/avocado/job-results/job-2020-02-25T23.58-d438849/...
> (90.53 s)
> RESULTS    : PASS 0 | ERROR 0 | FAIL 0 | SKIP 0 | WARN 0 | INTERRUPT 2 |
> CANCEL 0
> JOB TIME   : 181.22 s
>  ....
> 
> Have you noticed a similar performance change?
> Do you have any clue if there may be something changed here that could
> cause a slowdown?
> 
> Regards,
> Niek
> 
>