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List:       qemu-arm
Subject:    Re: [PATCH v2 2/4] accel/tcg: remove link between guest ram and TCG cache size
From:       Niek Linnenbank <nieklinnenbank () gmail ! com>
Date:       2020-02-28 20:17:00
Message-ID: CAPan3WrZZ6FtkY+ZNkMwVuTTaXSk9_99dW4=0LwkDqkn0rWUZA () mail ! gmail ! com
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On Fri, Feb 28, 2020 at 8:24 PM Alex Bennée <alex.bennee@linaro.org> wrote:

> Basing the TB cache size on the ram_size was always a little heuristic
> and was broken by a1b18df9a4 which caused ram_size not to be fully
> realised at the time we initialise the TCG translation cache.
>
> The current DEFAULT_CODE_GEN_BUFFER_SIZE may still be a little small
> but follow-up patches will address that.
>
> Fixes: a1b18df9a4
> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
> Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
> Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
>
Reviewed-by: Niek Linnenbank <nieklinnenbank@gmail.com>

Cc: Niek Linnenbank <nieklinnenbank@gmail.com>
> Cc: Igor Mammedov <imammedo@redhat.com>
> ---
>  accel/tcg/translate-all.c | 8 --------
>  1 file changed, 8 deletions(-)
>
> diff --git a/accel/tcg/translate-all.c b/accel/tcg/translate-all.c
> index 238b0e575bf..5b66af783b5 100644
> --- a/accel/tcg/translate-all.c
> +++ b/accel/tcg/translate-all.c
> @@ -938,15 +938,7 @@ static inline size_t size_code_gen_buffer(size_t
> tb_size)
>  {
>      /* Size the buffer.  */
>      if (tb_size == 0) {
> -#ifdef USE_STATIC_CODE_GEN_BUFFER
>          tb_size = DEFAULT_CODE_GEN_BUFFER_SIZE;
> -#else
> -        /* ??? Needs adjustments.  */
> -        /* ??? 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);
> -#endif
>      }
>      if (tb_size < MIN_CODE_GEN_BUFFER_SIZE) {
>          tb_size = MIN_CODE_GEN_BUFFER_SIZE;
> --
> 2.20.1
>
>

-- 
Niek Linnenbank

[Attachment #3 (text/html)]

<div dir="ltr"><div dir="ltr"><br></div><br><div class="gmail_quote"><div dir="ltr" \
class="gmail_attr">On Fri, Feb 28, 2020 at 8:24 PM Alex Bennée &lt;<a \
href="mailto:alex.bennee@linaro.org">alex.bennee@linaro.org</a>&gt; \
wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px \
0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">Basing the TB cache \
size on the ram_size was always a little heuristic<br> and was broken by a1b18df9a4 \
which caused ram_size not to be fully<br> realised at the time we initialise the TCG \
translation cache.<br> <br>
The current DEFAULT_CODE_GEN_BUFFER_SIZE may still be a little small<br>
but follow-up patches will address that.<br>
<br>
Fixes: a1b18df9a4<br>
Signed-off-by: Alex Bennée &lt;<a href="mailto:alex.bennee@linaro.org" \
                target="_blank">alex.bennee@linaro.org</a>&gt;<br>
Reviewed-by: Richard Henderson &lt;<a href="mailto:richard.henderson@linaro.org" \
                target="_blank">richard.henderson@linaro.org</a>&gt;<br>
Tested-by: Philippe Mathieu-Daudé &lt;<a href="mailto:philmd@redhat.com" \
target="_blank">philmd@redhat.com</a>&gt;<br></blockquote><div>Reviewed-by: Niek \
Linnenbank &lt;<a href="mailto:nieklinnenbank@gmail.com">nieklinnenbank@gmail.com</a>&gt;</div><div> \
<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px \
                0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
Cc: Niek Linnenbank &lt;<a href="mailto:nieklinnenbank@gmail.com" \
                target="_blank">nieklinnenbank@gmail.com</a>&gt;<br>
Cc: Igor Mammedov &lt;<a href="mailto:imammedo@redhat.com" \
                target="_blank">imammedo@redhat.com</a>&gt;<br>
---<br>
  accel/tcg/translate-all.c | 8 --------<br>
  1 file changed, 8 deletions(-)<br>
<br>
diff --git a/accel/tcg/translate-all.c b/accel/tcg/translate-all.c<br>
index 238b0e575bf..5b66af783b5 100644<br>
--- a/accel/tcg/translate-all.c<br>
+++ b/accel/tcg/translate-all.c<br>
@@ -938,15 +938,7 @@ static inline size_t size_code_gen_buffer(size_t tb_size)<br>
  {<br>
        /* Size the buffer.   */<br>
        if (tb_size == 0) {<br>
-#ifdef USE_STATIC_CODE_GEN_BUFFER<br>
              tb_size = DEFAULT_CODE_GEN_BUFFER_SIZE;<br>
-#else<br>
-            /* ??? Needs adjustments.   */<br>
-            /* ??? If we relax the requirement that CONFIG_USER_ONLY use the<br>
-                 static buffer, we could size this on RESERVED_VA, on the text<br>
-                 segment size of the executable, or continue to use the default.   \
                */<br>
-            tb_size = (unsigned long)(ram_size / 4);<br>
-#endif<br>
        }<br>
        if (tb_size &lt; MIN_CODE_GEN_BUFFER_SIZE) {<br>
              tb_size = MIN_CODE_GEN_BUFFER_SIZE;<br>
-- <br>
2.20.1<br>
<br>
</blockquote></div><br clear="all"><br>-- <br><div dir="ltr" \
class="gmail_signature"><div dir="ltr"><div>Niek \
Linnenbank<br><br></div></div></div></div>



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