Message ID | 1268817985-26172-2-git-send-email-apw@canonical.com |
---|---|
State | Accepted |
Delegated to: | Andy Whitcroft |
Headers | show |
It seems at least worth trying as everything that helps to debug is good as long as it does not impact normal usage. Andy Whitcroft wrote: > Enable MMIOTRACE to allow us to trace low level card operations. This is > commonly used to debug graphics issues particularly under Nouveau. > According to the documentation it is a near zero impact when disabled. > > Signed-off-by: Andy Whitcroft <apw@canonical.com> Acked-by: Stefan Bader <stefan.bader@canonical.com> > --- > debian.master/config/config.common.ubuntu | 3 ++- > 1 files changed, 2 insertions(+), 1 deletions(-) > > diff --git a/debian.master/config/config.common.ubuntu b/debian.master/config/config.common.ubuntu > index 0bca70a..989c14c 100644 > --- a/debian.master/config/config.common.ubuntu > +++ b/debian.master/config/config.common.ubuntu > @@ -2236,7 +2236,8 @@ CONFIG_MMC_TIFM_SD=m > # CONFIG_MMC_UNSAFE_RESUME is not set > CONFIG_MMC_VIA_SDMMC=m > CONFIG_MMC_WBSD=m > -# CONFIG_MMIOTRACE is not set > +CONFIG_MMIOTRACE=y > +# CONFIG_MMIOTRACE_TEST is not set > CONFIG_MMU=y > CONFIG_MMU_NOTIFIER=y > CONFIG_MM_OWNER=y
The benefit as a debugging tool makes this a very good option to turn on. It appears to add minimal overhead when not being used in debug mode, so I'm for this. On Wed, 2010-03-17 at 09:26 +0000, Andy Whitcroft wrote: > Enable MMIOTRACE to allow us to trace low level card operations. This is > commonly used to debug graphics issues particularly under Nouveau. > According to the documentation it is a near zero impact when disabled. > > Signed-off-by: Andy Whitcroft <apw@canonical.com> Acked-by: Colin King <colin.king@canonical.com> > --- > debian.master/config/config.common.ubuntu | 3 ++- > 1 files changed, 2 insertions(+), 1 deletions(-) > > diff --git a/debian.master/config/config.common.ubuntu b/debian.master/config/config.common.ubuntu > index 0bca70a..989c14c 100644 > --- a/debian.master/config/config.common.ubuntu > +++ b/debian.master/config/config.common.ubuntu > @@ -2236,7 +2236,8 @@ CONFIG_MMC_TIFM_SD=m > # CONFIG_MMC_UNSAFE_RESUME is not set > CONFIG_MMC_VIA_SDMMC=m > CONFIG_MMC_WBSD=m > -# CONFIG_MMIOTRACE is not set > +CONFIG_MMIOTRACE=y > +# CONFIG_MMIOTRACE_TEST is not set > CONFIG_MMU=y > CONFIG_MMU_NOTIFIER=y > CONFIG_MM_OWNER=y > -- > 1.7.0 > >
On Wed, Mar 17, 2010 at 09:26:24AM +0000, Andy Whitcroft wrote: > Enable MMIOTRACE to allow us to trace low level card operations. This is > commonly used to debug graphics issues particularly under Nouveau. > According to the documentation it is a near zero impact when disabled. "when enabled" I hope? > Signed-off-by: Andy Whitcroft <apw@canonical.com> > --- > debian.master/config/config.common.ubuntu | 3 ++- > 1 files changed, 2 insertions(+), 1 deletions(-) > > diff --git a/debian.master/config/config.common.ubuntu b/debian.master/config/config.common.ubuntu > index 0bca70a..989c14c 100644 > --- a/debian.master/config/config.common.ubuntu > +++ b/debian.master/config/config.common.ubuntu > @@ -2236,7 +2236,8 @@ CONFIG_MMC_TIFM_SD=m > # CONFIG_MMC_UNSAFE_RESUME is not set > CONFIG_MMC_VIA_SDMMC=m > CONFIG_MMC_WBSD=m > -# CONFIG_MMIOTRACE is not set > +CONFIG_MMIOTRACE=y > +# CONFIG_MMIOTRACE_TEST is not set > CONFIG_MMU=y > CONFIG_MMU_NOTIFIER=y > CONFIG_MM_OWNER=y > -- > 1.7.0 > > > -- > kernel-team mailing list > kernel-team@lists.ubuntu.com > https://lists.ubuntu.com/mailman/listinfo/kernel-team
On Wed, Mar 17, 2010 at 03:03:41AM -0700, Bryce Harrington wrote: > On Wed, Mar 17, 2010 at 09:26:24AM +0000, Andy Whitcroft wrote: > > Enable MMIOTRACE to allow us to trace low level card operations. This is > > commonly used to debug graphics issues particularly under Nouveau. > > According to the documentation it is a near zero impact when disabled. > > "when enabled" I hope? The cost is near-zero for having the MMIOTRACE option enabled with the trace collection turned off (the default). We take one additional branch in the mmio map/upmap paths which are non-critical initialisation/teardone paths in normal usage. The actual mmio operations are not affected at all. When we enable trace collection the overhead is high, taking a page fault for each access to the mmio mapping. -apw
On Wed, 2010-03-17 at 03:03 -0700, Bryce Harrington wrote: > On Wed, Mar 17, 2010 at 09:26:24AM +0000, Andy Whitcroft wrote: > > Enable MMIOTRACE to allow us to trace low level card operations. This is > > commonly used to debug graphics issues particularly under Nouveau. > > According to the documentation it is a near zero impact when disabled. > > "when enabled" I hope? > No; when it's enabled it's a huge performance hit. It's not uncommon for a mmio-traced nvidia blob to take multiple minutes to bring up X.
On Thu, 2010-03-18 at 16:43 +1100, Christopher James Halse Rogers wrote: > On Wed, 2010-03-17 at 03:03 -0700, Bryce Harrington wrote: > > On Wed, Mar 17, 2010 at 09:26:24AM +0000, Andy Whitcroft wrote: > > > Enable MMIOTRACE to allow us to trace low level card operations. This is > > > commonly used to debug graphics issues particularly under Nouveau. > > > According to the documentation it is a near zero impact when disabled. > > > > "when enabled" I hope? > > > No; when it's enabled it's a huge performance hit. It's not uncommon > for a mmio-traced nvidia blob to take multiple minutes to bring up X. > To be clear here: The kernel config option, when enabled, adds a new available tracer, which when itself is enabled, causes a huge performance hit. Enabling the kernel config option doesn't cause a huge performance hit in its own right. Scott
diff --git a/debian.master/config/config.common.ubuntu b/debian.master/config/config.common.ubuntu index 0bca70a..989c14c 100644 --- a/debian.master/config/config.common.ubuntu +++ b/debian.master/config/config.common.ubuntu @@ -2236,7 +2236,8 @@ CONFIG_MMC_TIFM_SD=m # CONFIG_MMC_UNSAFE_RESUME is not set CONFIG_MMC_VIA_SDMMC=m CONFIG_MMC_WBSD=m -# CONFIG_MMIOTRACE is not set +CONFIG_MMIOTRACE=y +# CONFIG_MMIOTRACE_TEST is not set CONFIG_MMU=y CONFIG_MMU_NOTIFIER=y CONFIG_MM_OWNER=y
Enable MMIOTRACE to allow us to trace low level card operations. This is commonly used to debug graphics issues particularly under Nouveau. According to the documentation it is a near zero impact when disabled. Signed-off-by: Andy Whitcroft <apw@canonical.com> --- debian.master/config/config.common.ubuntu | 3 ++- 1 files changed, 2 insertions(+), 1 deletions(-)