* [PATCH] net/qede: reduce the optimization level
@ 2025-09-03 11:32 Thierry Herbelot
2025-09-06 3:59 ` Stephen Hemminger
2025-09-08 7:04 ` [V2] net/qede: reduce the optimization level for gcc > 11 Thierry Herbelot
0 siblings, 2 replies; 6+ messages in thread
From: Thierry Herbelot @ 2025-09-03 11:32 UTC (permalink / raw)
To: dev
Cc: Thierry Herbelot, Thomas Monjalon, Devendra Singh Rawat,
Alok Prasad, Jerin Jacob, Olivier Matz, Edwin Brossette, stable
The qede PMD stopped working under Ubuntu-24.04 (using gcc-13) when
compiled with -O3 (default level for all DPDK code). A bug is opened
for this issue (see Link).
A first workaround is to just disable all optimizations (-O0), which
restores packet Rx with Qlogic NICs. However, the performance impact
is not acceptable (around 50% drop).
A better compromise is to use -O1 for the qede PMD:
- there is some perf impact,
- but the PMD is working as expected (packets are correctly received).
When compiling with both -O2 and -O3 and gcc-13, there is no packet
reception when using the qede PMD. The root cause could be missing
'volatile' keywords or missing memory barriers in the qede PMD code.
Link: https://bugs.dpdk.org/show_bug.cgi?id=1379
Signed-off-by: Thierry Herbelot <thierry.herbelot@6wind.com>
---
drivers/net/qede/base/meson.build | 1 +
drivers/net/qede/meson.build | 1 +
2 files changed, 2 insertions(+)
diff --git a/drivers/net/qede/base/meson.build b/drivers/net/qede/base/meson.build
index a6dad3ec7bcc..6c8800a3f48f 100644
--- a/drivers/net/qede/base/meson.build
+++ b/drivers/net/qede/base/meson.build
@@ -55,3 +55,4 @@ foreach flag: error_cflags
base_cflags += flag
endif
endforeach
+base_cflags += '-O1'
diff --git a/drivers/net/qede/meson.build b/drivers/net/qede/meson.build
index e1b21d6ff5cd..3c2a5205732a 100644
--- a/drivers/net/qede/meson.build
+++ b/drivers/net/qede/meson.build
@@ -22,3 +22,4 @@ sources = files(
if cc.has_argument('-Wno-format-nonliteral')
cflags += '-Wno-format-nonliteral'
endif
+cflags += '-O1'
--
2.39.2
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] net/qede: reduce the optimization level
2025-09-03 11:32 [PATCH] net/qede: reduce the optimization level Thierry Herbelot
@ 2025-09-06 3:59 ` Stephen Hemminger
2025-09-08 7:04 ` [V2] net/qede: reduce the optimization level for gcc > 11 Thierry Herbelot
1 sibling, 0 replies; 6+ messages in thread
From: Stephen Hemminger @ 2025-09-06 3:59 UTC (permalink / raw)
To: Thierry Herbelot
Cc: dev, Thomas Monjalon, Devendra Singh Rawat, Alok Prasad,
Jerin Jacob, Olivier Matz, Edwin Brossette, stable
On Wed, 3 Sep 2025 13:32:52 +0200
Thierry Herbelot <thierry.herbelot@6wind.com> wrote:
> The qede PMD stopped working under Ubuntu-24.04 (using gcc-13) when
> compiled with -O3 (default level for all DPDK code). A bug is opened
> for this issue (see Link).
>
> A first workaround is to just disable all optimizations (-O0), which
> restores packet Rx with Qlogic NICs. However, the performance impact
> is not acceptable (around 50% drop).
>
> A better compromise is to use -O1 for the qede PMD:
> - there is some perf impact,
> - but the PMD is working as expected (packets are correctly received).
>
> When compiling with both -O2 and -O3 and gcc-13, there is no packet
> reception when using the qede PMD. The root cause could be missing
> 'volatile' keywords or missing memory barriers in the qede PMD code.
>
> Link: https://bugs.dpdk.org/show_bug.cgi?id=1379
> Signed-off-by: Thierry Herbelot <thierry.herbelot@6wind.com>
Since GCC 14 and 15 are available do they fix the problem?
If so, the the hack should be limited to Gcc 13 and with
more complete comment.
^ permalink raw reply [flat|nested] 6+ messages in thread
* [V2] net/qede: reduce the optimization level for gcc > 11
2025-09-03 11:32 [PATCH] net/qede: reduce the optimization level Thierry Herbelot
2025-09-06 3:59 ` Stephen Hemminger
@ 2025-09-08 7:04 ` Thierry Herbelot
2025-09-08 19:59 ` Stephen Hemminger
2025-09-09 5:40 ` [V3] " Thierry Herbelot
1 sibling, 2 replies; 6+ messages in thread
From: Thierry Herbelot @ 2025-09-08 7:04 UTC (permalink / raw)
To: dev
Cc: Thierry Herbelot, Thomas Monjalon, Devendra Singh Rawat,
Alok Prasad, Jerin Jacob, Olivier Matz, Edwin Brossette, stable
The qede PMD stopped working under Ubuntu-24.04 (using gcc-13) when
compiled with -O3 (default level for all DPDK code). A bug is opened
for this issue (see Link). The same issue is also seen with gcc-12
and gcc-14.
A first workaround is to just disable all optimizations (-O0), which
restores packet Rx with Qlogic NICs. However, the performance impact
is not acceptable (around 50% drop).
A better compromise is to use -O1 for the qede PMD:
- there is some perf impact,
- but the PMD is working as expected (packets are correctly received).
When compiling with both -O2 and -O3 and gcc > 11, there is no packet
reception when using the qede PMD. The root cause could be missing
'volatile' keywords or missing memory barriers in the qede PMD code.
Link: https://bugs.dpdk.org/show_bug.cgi?id=1379
Signed-off-by: Thierry Herbelot <thierry.herbelot@6wind.com>
---
V2: be more precise when dropping optimization level (only for gcc > 11)
---
drivers/net/qede/base/meson.build | 4 ++++
drivers/net/qede/meson.build | 4 ++++
2 files changed, 8 insertions(+)
diff --git a/drivers/net/qede/base/meson.build b/drivers/net/qede/base/meson.build
index a6dad3ec7bcc..130835cc31b1 100644
--- a/drivers/net/qede/base/meson.build
+++ b/drivers/net/qede/base/meson.build
@@ -55,3 +55,7 @@ foreach flag: error_cflags
base_cflags += flag
endif
endforeach
+# no packet Rx with gcc > 11 with compiling with default -O3 or -O2
+if (cc.get_id() == 'gcc' and cc.version().version_compare('>11.0'))
+ base_cflags += '-O1'
+endif
diff --git a/drivers/net/qede/meson.build b/drivers/net/qede/meson.build
index e1b21d6ff5cd..e4268883ff93 100644
--- a/drivers/net/qede/meson.build
+++ b/drivers/net/qede/meson.build
@@ -22,3 +22,7 @@ sources = files(
if cc.has_argument('-Wno-format-nonliteral')
cflags += '-Wno-format-nonliteral'
endif
+# no packet Rx with gcc > 11 with compiling with default -O3 or -O2
+if (cc.get_id() == 'gcc' and cc.version().version_compare('>11.0'))
+ cflags += '-O1'
+endif
--
2.39.2
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [V2] net/qede: reduce the optimization level for gcc > 11
2025-09-08 7:04 ` [V2] net/qede: reduce the optimization level for gcc > 11 Thierry Herbelot
@ 2025-09-08 19:59 ` Stephen Hemminger
2025-09-09 5:27 ` Thierry Herbelot
2025-09-09 5:40 ` [V3] " Thierry Herbelot
1 sibling, 1 reply; 6+ messages in thread
From: Stephen Hemminger @ 2025-09-08 19:59 UTC (permalink / raw)
To: Thierry Herbelot
Cc: dev, Thomas Monjalon, Devendra Singh Rawat, Alok Prasad,
Jerin Jacob, Olivier Matz, Edwin Brossette, stable
On Mon, 8 Sep 2025 09:04:13 +0200
Thierry Herbelot <thierry.herbelot@6wind.com> wrote:
> +# no packet Rx with gcc > 11 with compiling with default -O3 or -O2
> +if (cc.get_id() == 'gcc' and cc.version().version_compare('>11.0'))
> + base_cflags += '-O1'
> +endif
Did you test with Gcc 14 and 15, it may be the bug is already fixed.
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [V2] net/qede: reduce the optimization level for gcc > 11
2025-09-08 19:59 ` Stephen Hemminger
@ 2025-09-09 5:27 ` Thierry Herbelot
0 siblings, 0 replies; 6+ messages in thread
From: Thierry Herbelot @ 2025-09-09 5:27 UTC (permalink / raw)
To: Stephen Hemminger
Cc: dev, Thomas Monjalon, Devendra Singh Rawat, Alok Prasad,
Jerin Jacob, Olivier Matz, Edwin Brossette, stable
On 9/8/25 21:59, Stephen Hemminger wrote:
> On Mon, 8 Sep 2025 09:04:13 +0200
> Thierry Herbelot <thierry.herbelot@6wind.com> wrote:
>
>> +# no packet Rx with gcc > 11 with compiling with default -O3 or -O2
>> +if (cc.get_id() == 'gcc' and cc.version().version_compare('>11.0'))
>> + base_cflags += '-O1'
>> +endif
>
> Did you test with Gcc 14 and 15, it may be the bug is already fixed.
As said in the commit log:
"The same issue is also seen with gcc-12 and gcc-14."
I did not test with gcc-15.
The issue is not seen with clang20 (qede PMD compiled with -O3 works as
expected).
Best regards
Thierry
--
Thierry Herbelot
CSE - Titulaire au collège Cadres
Senior Software Engineer
http://www.6wind.com/
Follow us:
https://www.linkedin.com/company/6wind/
https://twitter.com/6WINDsoftware
https://www.youtube.com/user/6windsoftware
^ permalink raw reply [flat|nested] 6+ messages in thread
* [V3] net/qede: reduce the optimization level for gcc > 11
2025-09-08 7:04 ` [V2] net/qede: reduce the optimization level for gcc > 11 Thierry Herbelot
2025-09-08 19:59 ` Stephen Hemminger
@ 2025-09-09 5:40 ` Thierry Herbelot
1 sibling, 0 replies; 6+ messages in thread
From: Thierry Herbelot @ 2025-09-09 5:40 UTC (permalink / raw)
To: dev
Cc: Thierry Herbelot, Thomas Monjalon, Devendra Singh Rawat,
Alok Prasad, Jerin Jacob, Olivier Matz, Edwin Brossette, stable
The qede PMD stopped working under Ubuntu-24.04 (using gcc-13) when
compiled with -O3 (default level for all DPDK code). A bug is opened
for this issue (see Link). The same issue is also seen with gcc-12
and gcc-14. The issue is not seen with clang-20.
A first workaround is to just disable all optimizations (-O0), which
restores packet Rx with Qlogic NICs. However, the performance impact
is not acceptable (around 50% drop).
A better compromise is to use -O1 for the qede PMD:
- there is some perf impact,
- but the PMD is working as expected (packets are correctly received).
When compiling with both -O2 and -O3 and gcc > 11, there is no packet
reception when using the qede PMD. The root cause could be missing
'volatile' keywords or missing memory barriers in the qede PMD code.
Link: https://bugs.dpdk.org/show_bug.cgi?id=1379
Signed-off-by: Thierry Herbelot <thierry.herbelot@6wind.com>
---
V2: be more precise when dropping optimization level (only for gcc > 11)
V3: even more precise: the issue appears with gcc-12
---
drivers/net/qede/base/meson.build | 4 ++++
drivers/net/qede/meson.build | 4 ++++
2 files changed, 8 insertions(+)
diff --git a/drivers/net/qede/base/meson.build b/drivers/net/qede/base/meson.build
index a6dad3ec7bcc..acab6e8ac938 100644
--- a/drivers/net/qede/base/meson.build
+++ b/drivers/net/qede/base/meson.build
@@ -55,3 +55,7 @@ foreach flag: error_cflags
base_cflags += flag
endif
endforeach
+# no packet Rx with gcc > 11 with compiling with default -O3 or -O2
+if (cc.get_id() == 'gcc' and cc.version().version_compare('>=12.0'))
+ base_cflags += '-O1'
+endif
diff --git a/drivers/net/qede/meson.build b/drivers/net/qede/meson.build
index e1b21d6ff5cd..86c3503a82f6 100644
--- a/drivers/net/qede/meson.build
+++ b/drivers/net/qede/meson.build
@@ -22,3 +22,7 @@ sources = files(
if cc.has_argument('-Wno-format-nonliteral')
cflags += '-Wno-format-nonliteral'
endif
+# no packet Rx with gcc > 11 with compiling with default -O3 or -O2
+if (cc.get_id() == 'gcc' and cc.version().version_compare('>=12.0'))
+ cflags += '-O1'
+endif
--
2.39.2
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2025-09-09 5:40 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
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2025-09-03 11:32 [PATCH] net/qede: reduce the optimization level Thierry Herbelot
2025-09-06 3:59 ` Stephen Hemminger
2025-09-08 7:04 ` [V2] net/qede: reduce the optimization level for gcc > 11 Thierry Herbelot
2025-09-08 19:59 ` Stephen Hemminger
2025-09-09 5:27 ` Thierry Herbelot
2025-09-09 5:40 ` [V3] " Thierry Herbelot
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