10 Feb
2023
10 Feb
'23
12:54 a.m.
Hi all,
I was running into some odd behaviour while debugging—specifically, I
found that specifying the d3d channel in WINEDEBUG was cutting my
performance in half, even when disabling logging, and even when it
should have been functionally identical to a run without the d3d channel
specified.
I was able to "fix" this inconsistency with this diff:
diff --git a/dlls/ntdll/thread.c b/dlls/ntdll/thread.c
index 1bd8f900d22..f0e4b824918 100644
--- a/dlls/ntdll/thread.c
+++ b/dlls/ntdll/thread.c
@@ -103,7 +103,11 @@ unsigned char __cdecl __wine_dbg_get_channel_flags(
struct __wine_debug_channel
{
pos = (min + max) / 2;
res = strcmp( channel->name, debug_options[pos].name );
- if (!res) return debug_options[pos].flags;
+ if (!res)
+ {
+ if (channel->flags & (1 << __WINE_DBCL_INIT))
channel->flags = debug_options[pos].flags;
+ return debug_options[pos].flags;
+ }
if (res < 0) max = pos - 1;
else min = pos + 1;
}
Which makes sense to some degree, but leaves three questions unanswered,
which I was hoping someone might be able to cluebat me on:
(1) Why does setting channel->flags affect performance at all? I'm
thoroughly baffled by this one.
(2) Why was this diff not applied in the first place? (Simple oversight?)
(3) Why does __WINE_DBCL_INIT even exist, if its only purpose is to
guard out a single assignment?
--Zeb
10 Feb
10 Feb
6:18 a.m.
On 2/10/23 01:54, Zebediah Figura wrote:
Hi all,
I was running into some odd behaviour while debugging—specifically, I
found that specifying the d3d channel in WINEDEBUG was cutting my
performance in half, even when disabling logging, and even when it
should have been functionally identical to a run without the d3d channel
specified.
I was able to "fix" this inconsistency with this diff:
diff --git a/dlls/ntdll/thread.c b/dlls/ntdll/thread.c
index 1bd8f900d22..f0e4b824918 100644
--- a/dlls/ntdll/thread.c
+++ b/dlls/ntdll/thread.c
@@ -103,7 +103,11 @@ unsigned char __cdecl __wine_dbg_get_channel_flags(
struct __wine_debug_channel
{
pos = (min + max) / 2;
res = strcmp( channel->name, debug_options[pos].name );
- if (!res) return debug_options[pos].flags;
+ if (!res)
+ {
+ if (channel->flags & (1 << __WINE_DBCL_INIT))
channel->flags = debug_options[pos].flags;
+ return debug_options[pos].flags;
+ }
if (res < 0) max = pos - 1;
else min = pos + 1;
}
Which makes sense to some degree, but leaves three questions unanswered,
which I was hoping someone might be able to cluebat me on:
(1) Why does setting channel->flags affect performance at all? I'm
thoroughly baffled by this one.
(2) Why was this diff not applied in the first place? (Simple oversight?)
(3) Why does __WINE_DBCL_INIT even exist, if its only purpose is to
guard out a single assignment?
--Zeb
Probably to allow changing the selected channels dynamically, through
process monitor for instance.
--
Rémi Bernon <rbernon(a)codeweavers.com>
6:12 p.m.
On 2/10/23 00:18, Rémi Bernon wrote:
I'm not sure which question this answers, but I don't think I understand
it? winedbg and taskmgr just set the flags directly; they don't touch
__WINE_DBCL_INIT, and I don't see why they'd need to.
(1) Why does
setting channel->flags affect performance at all? I'm
thoroughly baffled by this one.
(2) Why was this diff not applied in the first place? (Simple oversight?)
(3) Why does __WINE_DBCL_INIT even exist, if its only purpose is to
guard out a single assignment?
--Zeb
Probably to allow changing the selected channels dynamically, through
process monitor for instance.
7:04 p.m.
On 2/10/23 19:12, Zebediah Figura wrote:
On 2/10/23 00:18, Rémi Bernon wrote:
I'm not sure which question this answers, but I don't think I understand
it? winedbg and taskmgr just set the flags directly; they don't touch
__WINE_DBCL_INIT, and I don't see why they'd need to.
They can't change the flags in each of the translation units debug
channels. What they do is change the debug options in the process PEB.
In order to support the runtime modification, the TU debug channels need
to keep their __WINE_DBCL_INIT bit set, so __wine_dbg_get_channel_flags
is always called, and the debug option updated from the PEB.
Only channels which aren't explicitly specified clear their
__WINE_DBCL_INIT bit, after copying the default debug options.
The default options (all) cannot be modified dynamically, or at least
only takes effect the first time __wine_dbg_get_channel_flags is called
for a given TU debug channel.
--
Rémi Bernon <rbernon(a)codeweavers.com>
(1) Why
does setting channel->flags affect performance at all? I'm
thoroughly baffled by this one.
(2) Why was this diff not applied in the first place? (Simple
oversight?)
(3) Why does __WINE_DBCL_INIT even exist, if its only purpose is to
guard out a single assignment?
--Zeb
Probably to allow changing the selected channels dynamically, through
process monitor for instance.
7:36 p.m.
On 2/10/23 20:04, Rémi Bernon wrote:
On 2/10/23 19:12, Zebediah Figura wrote:
Correction, it's actually not __WINE_DBCL_INIT but rather their default
value, which contains all the bits. The logic is otherwise the same, the
TU channel bits are only eventually cleared for the default options, for
the reasons described here.
On 2/10/23 00:18, Rémi Bernon wrote:
I'm not sure which question this answers, but I don't think I
understand it? winedbg and taskmgr just set the flags directly; they
don't touch __WINE_DBCL_INIT, and I don't see why they'd need to.
They can't change the flags in each of the translation units debug
channels. What they do is change the debug options in the process PEB.
In order to support the runtime modification, the TU debug channels need
to keep their __WINE_DBCL_INIT bit set, so __wine_dbg_get_channel_flags
is always called, and the debug option updated from the PEB.
(1) Why
does setting channel->flags affect performance at all? I'm
thoroughly baffled by this one.
(2) Why was this diff not applied in the first place? (Simple
oversight?)
(3) Why does __WINE_DBCL_INIT even exist, if its only purpose is to
guard out a single assignment?
--Zeb
Probably to allow changing the selected channels dynamically, through
process monitor for instance.
Only channels which aren't explicitly specified clear their
__WINE_DBCL_INIT bit, after copying the default debug options.
The default options (all) cannot be modified dynamically, or at least
only takes effect the first time __wine_dbg_get_channel_flags is called
for a given TU debug channel.
--
Rémi Bernon <rbernon(a)codeweavers.com>
14 Feb
14 Feb
1:07 a.m.
On 2/10/23 13:36, Rémi Bernon wrote:
On 2/10/23 20:04, Rémi Bernon wrote:
Thank you, that explains why the logic is arranged like it is.
I'm inclined to think we should find another way to achieve this;
spending hours trying to debug a performance drop from disabling logging
channels is really not something I want to happen to anyone else. I'll
see what I can achieve.
This doesn't explain why __WINE_DBCL_INIT exists, but I can only assume
that at this point there's no particularly good reason.
On 2/10/23 19:12, Zebediah Figura wrote:
Correction, it's actually not __WINE_DBCL_INIT but rather their default
value, which contains all the bits. The logic is otherwise the same, the
TU channel bits are only eventually cleared for the default options, for
the reasons described here.
On 2/10/23 00:18, Rémi Bernon wrote:
They can't change the flags in each of the translation units debug
channels. What they do is change the debug options in the process PEB.
In order to support the runtime modification, the TU debug channels
need to keep their __WINE_DBCL_INIT bit set, so
__wine_dbg_get_channel_flags is always called, and the debug option
updated from the PEB.
> (1) Why does setting channel->flags affect
performance at all? I'm
> thoroughly baffled by this one.
>
> (2) Why was this diff not applied in the first place? (Simple
> oversight?)
>
> (3) Why does __WINE_DBCL_INIT even exist, if its only purpose is to
> guard out a single assignment?
>
> --Zeb
>
Probably to allow changing the selected channels dynamically,
through process monitor for instance.
I'm not sure which question this answers, but I don't think I
understand it? winedbg and taskmgr just set the flags directly; they
don't touch __WINE_DBCL_INIT, and I don't see why they'd need to.
Only channels which aren't explicitly specified clear their
__WINE_DBCL_INIT bit, after copying the default debug options.
The default options (all) cannot be modified dynamically, or at least
only takes effect the first time __wine_dbg_get_channel_flags is
called for a given TU debug channel.
10 Feb
10 Feb
5:59 p.m.
On 2/9/23 18:54, Zebediah Figura wrote:
(1) Why does setting channel->flags affect
performance at all? I'm
thoroughly baffled by this one.
Evan Tang provided me with the cluebat privately—it's because
__WINE_DBCL_TRACE is always set, so we end up always calling
__wine_dbg_header() [which will then discard the message]. So we
probably really should fix this :x
447
days inactive
451
days old
6 comments
2 participants
participants (2)
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Rémi Bernon -
Zebediah Figura