On Tue, Feb 4, 2025 at 10:03 PM Steven Rostedt wrote:
>
> On Tue, 4 Feb 2025 19:56:09 -0500
> Joel Fernandes wrote:
>
> > > Here is the RFC I had sent that Peter is referring
> >
> > FWIW, I second the idea of a new syscall for this than (ab)using rseq
> > and also independence from preemption me
On Tue, 4 Feb 2025 19:56:09 -0500
Joel Fernandes wrote:
> > Here is the RFC I had sent that Peter is referring
>
> FWIW, I second the idea of a new syscall for this than (ab)using rseq
> and also independence from preemption method. I agree that something
> generic is better than relying on pr
On Thu, Jan 30, 2025 at 03:21:36PM -0500, Steven Rostedt wrote:
> Coming back from this. It would be fine if we could do the back trace when
> we come back from the scheduler, so it should not be an issue if the task
> even has to schedule again to fault in the sframe information.
So there would b
On Thu, Jan 30, 2025 at 01:39:52PM -0800, Indu Bhagat wrote:
> On 1/28/25 6:02 PM, Josh Poimboeuf wrote:
> > However, if we're going that route, we might want to even consider a
> > completely revamped data layout. For example:
> >
> > One insight is that the vast majority of (cfa, fp, ra) tuples
> On Feb 4, 2025, at 5:44 PM, Prakash Sangappa
> wrote:
>
>
>
>> On Feb 1, 2025, at 10:11 AM, Peter Zijlstra wrote:
>>
>>> On Sat, Feb 01, 2025 at 07:47:32AM -0500, Steven Rostedt wrote:
>>>
>>>
>>> On February 1, 2025 6:59:06 AM EST, Peter Zijlstra
>>> wrote:
>>>
I still have
On Tue, 4 Feb 2025 17:20:45 -0500
Steven Rostedt wrote:
> x = rec->counter
>
> x * (x - 1) * 1000 = (2^32 - 1) // use minus 1 just to be sure
> x * (x - 1) = (2^32 - 1) / 1000
> x^2 - x = (2^32 - 1) / 1000
> x^2 - x - (2^32 - 1) / 1000 = 0
>
> x = (-b +/- sqrt(b^2 - 4ac)) / 2a
>
> a
On Wed, 5 Feb 2025 00:13:26 +
Martin Kelly wrote:
> I'm not necessarily a qualified reviewer for this patch, but I'm very
> interested in seeing it or a similar solution get merged, as the impact
> when it hits is significant (silent failure) and not easy to detect or
> work around. Is there
On Thu, 2025-01-02 at 18:26 -0500, Steven Rostedt wrote:
> From: Steven Rostedt
>
> When a function is annotated as "weak" and is overridden, the code is
> not
> removed. If it is traced, the fentry/mcount location in the weak
> function
> will be referenced by the "__mcount_loc" section. This wi
On Tue, Feb 04, 2025 at 11:02:42PM +, Alexei Starovoitov wrote:
> On Tue, Feb 4, 2025 at 7:04 PM Namhyung Kim wrote:
> >
> > Hello,
> >
> > On Tue, Feb 04, 2025 at 10:34:41AM -0800, Charlie Jenkins wrote:
> > > On Tue, Feb 04, 2025 at 05:18:42PM +, Alexei Starovoitov wrote:
> > > > On Tue,
On Tue, Feb 4, 2025 at 7:04 PM Namhyung Kim wrote:
>
> Hello,
>
> On Tue, Feb 04, 2025 at 10:34:41AM -0800, Charlie Jenkins wrote:
> > On Tue, Feb 04, 2025 at 05:18:42PM +, Alexei Starovoitov wrote:
> > > On Tue, Feb 4, 2025 at 12:10 AM Charlie Jenkins
> > > wrote:
> > > >
> > > > The quiet
On Tue, 4 Feb 2025 10:43:02 +0300
Nikolay Kuratov wrote:
> Thank you for the review!
>
> `counter > rec->counter` check does not protect us from overflows,
> so this could mislead especially with the comment included.
Ah you're right, as there's a big multiplication there.
>
> I think we sho
On Tue, Feb 04, 2025 at 05:34:09PM +0100, Sebastian Andrzej Siewior wrote:
> On 2025-02-04 03:51:48 [-0800], Paul E. McKenney wrote:
> > On Tue, Feb 04, 2025 at 11:26:11AM +0100, Sebastian Andrzej Siewior wrote:
> > > On 2025-01-30 10:53:19 [-0800], Paul E. McKenney wrote:
> > > > The timer and hrt
On Thu, Jan 30, 2025 at 01:21:21PM -0800, Indu Bhagat wrote:
> > Yeah, and it's actually bothering me quite a lot 🙂 I have a tentative
> > proposal, maybe we can discuss this for SFrame v3? Let me briefly
> > outline the idea.
> >
>
> I looked at the idea below. It could work wrt unaligned acces
On Thu, Jan 30, 2025 at 05:38:24PM +0100, Jens Remus wrote:
> Add a similar debug message for SFRame FDE user copy failures?
>
> diff --git a/kernel/unwind/sframe.c b/kernel/unwind/sframe.c
>
> @@ -125,6 +125,7 @@ static __always_inline int __find_fde(struct
> sframe_section *sec,
> retu
On Thu, Jan 30, 2025 at 07:51:15PM +, Weinan Liu wrote:
> Nit: swap() might be a simplify way to alternate pointers between two
> fre_addr[] entries.
>
> For example,
>
> static __always_inline int __find_fre(struct sframe_section *sec,
> struct sframe_fde
On Thu, Jan 30, 2025 at 05:17:33PM +0100, Jens Remus wrote:
> On 22.01.2025 03:31, Josh Poimboeuf wrote:
> > When debugging sframe issues, the error messages aren't all that helpful
> > without knowing what file a corresponding .sframe section belongs to.
> > Prefix debug output strings with the fi
Hello,
On Tue, Feb 04, 2025 at 10:34:41AM -0800, Charlie Jenkins wrote:
> On Tue, Feb 04, 2025 at 05:18:42PM +, Alexei Starovoitov wrote:
> > On Tue, Feb 4, 2025 at 12:10 AM Charlie Jenkins
> > wrote:
> > >
> > > The quiet infrastructure was moved out of Makefile.build to accomidate
> > > th
On Thu, Jan 30, 2025 at 04:47:00PM +0100, Jens Remus wrote:
> On 22.01.2025 03:31, Josh Poimboeuf wrote:
> > +struct sframe_fre {
> > + unsigned intsize;
> > + s32 ip_off;
>
> The IP offset (from function start) in the SFrame V2 FDE is unsigned:
>
> u32 ip_off;
Indeed.
> > +
On Thu, Jan 30, 2025 at 07:07:32AM -0800, Indu Bhagat wrote:
> On 1/21/25 6:31 PM, Josh Poimboeuf wrote:
> > + for (i = 0; i < fde->fres_num; i++) {
> > + int ret;
> > +
> > + /*
> > +* Alternate between the two fre_addr[] entries for 'fre' and
> > +* '
On Tue, Feb 04, 2025 at 05:18:42PM +, Alexei Starovoitov wrote:
> On Tue, Feb 4, 2025 at 12:10 AM Charlie Jenkins wrote:
> >
> > The quiet infrastructure was moved out of Makefile.build to accomidate
> > the new syscall table generation scripts in perf. Syscall table
> > generation wanted to a
On Wed, Jan 29, 2025 at 04:02:34PM -0800, Andrii Nakryiko wrote:
> On Tue, Jan 28, 2025 at 6:02 PM Josh Poimboeuf wrote:
> I'm not sure about this chunked lookup approach for arbitrary user
> space applications. Those executable sections can be a) big and b)
> discontiguous. E.g., one of the produ
On Tue, Feb 4, 2025 at 12:10 AM Charlie Jenkins wrote:
>
> The quiet infrastructure was moved out of Makefile.build to accomidate
> the new syscall table generation scripts in perf. Syscall table
> generation wanted to also be able to be quiet, so instead of again
> copying the code to set the qui
Purva Yeshi writes:
> Move the "debugging" entry to the top in Documentation/trace/index.rst.
> Turn index.rst into a good starting point for people wanting to learn
> about tracing. Make it the first document users see, as it serves as a
> tracing tutorial
>
> Signed-off-by: Purva Yeshi
> ---
On 2025-02-04 03:51:48 [-0800], Paul E. McKenney wrote:
> On Tue, Feb 04, 2025 at 11:26:11AM +0100, Sebastian Andrzej Siewior wrote:
> > On 2025-01-30 10:53:19 [-0800], Paul E. McKenney wrote:
> > > The timer and hrtimer softirq processing has moved to dedicated threads
> > > for kernels built with
On Tue, 4 Feb 2025 16:30:53 +0100
Peter Zijlstra wrote:
> If you go back and reread that initial thread, you'll find the 50us is
> below the scheduling latency that random test box already had.
>
> I'm sure more modern systems will have a lower number, and slower
> systems will have a larger num
On Tue, Feb 04, 2025 at 07:51:00AM -0500, Steven Rostedt wrote:
> On Tue, 4 Feb 2025 10:16:13 +0100
> Peter Zijlstra wrote:
>
> > And yes, you can still use the whole 'delay preemption' hint for RT
> > tasks just fine. Spinlocks isn't the only thing. It can be used to make
> > any RSEQ section mo
n Tue, 4 Feb 2025 08:16:53 -0500
Steven Rostedt wrote:
> On Tue, 4 Feb 2025 07:51:00 -0500
> Steven Rostedt wrote:
>
> > > I'm so confused, WTF do you then need the lazy crap?
>
> IOW, the "lazy crap" was created to solve this very issue. The holding of
> sleeping spin locks interrupted by a
Move the "debugging" entry to the top in Documentation/trace/index.rst.
Turn index.rst into a good starting point for people wanting to learn
about tracing. Make it the first document users see, as it serves as a
tracing tutorial
Signed-off-by: Purva Yeshi
---
Documentation/trace/index.rst | 2
po 3. 2. 2025 v 10:04 odesílatel Tomas Glozar napsal:
> A proof-of-concept bpftrace script using this feature:
> https://gitlab.com/-/snippets/4801190
>
I added another PoC using event histograms to the snippet. That one
captures data from all CPUs, and thus can be used for testing on
machines wi
The kmem_cache_free tracepoint includes a "name" field, which allows
for easy identification and filtering of specific kmem's. However, the
kmem_cache_alloc tracepoint lacks this field, making it difficult to
pair corresponding alloc and free events for analysis.
Add the "name" field to kmem_cache
On Tue, 4 Feb 2025 07:51:00 -0500
Steven Rostedt wrote:
> > I'm so confused, WTF do you then need the lazy crap?
IOW, the "lazy crap" was created to solve this very issue. The holding of
sleeping spin locks interrupted by a scheduler tick. I'm just giving user
space the same feature that we gave
On Fri, 17 Jan 2025 07:55:22 -0500, Lukas Bulwahn wrote:
> Commit a3ed4157b7d8 ("fgraph: Replace fgraph_ret_regs with ftrace_regs")
> replaces the config HAVE_FUNCTION_GRAPH_RETVAL with the config
> HAVE_FUNCTION_GRAPH_FREGS, and it replaces all the select commands in the
> various architecture Kco
On Tue, 4 Feb 2025 10:16:13 +0100
Peter Zijlstra wrote:
> And yes, you can still use the whole 'delay preemption' hint for RT
> tasks just fine. Spinlocks isn't the only thing. It can be used to make
> any RSEQ section more likely to succeed.
>
>
> > Patch 2 changes that to do what you wrote th
On Tue, Feb 04, 2025 at 12:44:25PM +0100, Lukas Bulwahn wrote:
> On Tue, Feb 4, 2025 at 12:36 PM Will Deacon wrote:
> >
> > On Fri, Jan 17, 2025 at 07:55:22AM -0500, Lukas Bulwahn wrote:
> > > From: Lukas Bulwahn
> > >
> > > Commit a3ed4157b7d8 ("fgraph: Replace fgraph_ret_regs with ftrace_regs")
On Tue, Feb 04, 2025 at 11:26:11AM +0100, Sebastian Andrzej Siewior wrote:
> On 2025-01-30 10:53:19 [-0800], Paul E. McKenney wrote:
> > The timer and hrtimer softirq processing has moved to dedicated threads
> > for kernels built with CONFIG_IRQ_FORCED_THREADING=y. This results in
> > timers not
On Tue, Feb 4, 2025 at 12:36 PM Will Deacon wrote:
>
> On Fri, Jan 17, 2025 at 07:55:22AM -0500, Lukas Bulwahn wrote:
> > From: Lukas Bulwahn
> >
> > Commit a3ed4157b7d8 ("fgraph: Replace fgraph_ret_regs with ftrace_regs")
> > replaces the config HAVE_FUNCTION_GRAPH_RETVAL with the config
> > HAV
On Fri, Jan 17, 2025 at 07:55:22AM -0500, Lukas Bulwahn wrote:
> From: Lukas Bulwahn
>
> Commit a3ed4157b7d8 ("fgraph: Replace fgraph_ret_regs with ftrace_regs")
> replaces the config HAVE_FUNCTION_GRAPH_RETVAL with the config
> HAVE_FUNCTION_GRAPH_FREGS, and it replaces all the select commands i
On 2025-01-30 10:53:19 [-0800], Paul E. McKenney wrote:
> The timer and hrtimer softirq processing has moved to dedicated threads
> for kernels built with CONFIG_IRQ_FORCED_THREADING=y. This results in
> timers not expiring until later in early boot, which in turn causes the
> RCU Tasks self-tests
On Mon, 3 Feb 2025 22:33:48 +0100
Gabriel de Perthuis wrote:
> Hello,
>
> I got errors building Linux 6.14-rc1 that were solved by reverting this
> patch and the one after (19/20 and 20/20).
>
> Errors look like:
>
> In file included from ./arch/x86/include/asm/asm-prototypes.h:2,
>
On Mon, Feb 03, 2025 at 11:45:37AM -0500, Steven Rostedt wrote:
> > Lazy only applies to fair (and whatever bpf things end up using
> > resched_curr_lazy()).
>
> Is that a problem? User spin locks for RT tasks are very dangerous. If an
> RT task preempts the owner that is of lower priority, it ca
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