On Wed, 20 Dec 2023 18:48:43 +0900
Masami Hiramatsu (Google) wrote:
> > From: "Tzvetomir Stoyanov (VMware)"
> >
> > In order to introduce sub-buffer size per ring buffer, some internal
> > refactoring is needed. As ring_buffer_print_page_header() will depend on
> > the trace_buffer structure,
From: "Steven Rostedt (Google)"
The comparisons to PAGE_SIZE were all converted to use the
buffer->subbuf_order, but the use of PAGE_MASK was missed.
Convert all the PAGE_MASK usages over to:
(PAGE_SIZE << cpu_buffer->buffer->subbuf_order) - 1
Fixes: TBD ("r
On Tue, 19 Dec 2023 18:45:54 +
Vincent Donnefort wrote:
> The tracing ring-buffers can be stored on disk or sent to network
> without any copy via splice. However the later doesn't allow real time
> processing of the traces. A solution is to give userspace direct access
> to the ring-buffer
From: "Steven Rostedt (Google)"
Using page order for deciding what the size of the ring buffer sub buffers
are is exposing a bit too much of the implementation. Although the sub
buffers are only allocated in orders of pages, allow the user to specify
the minimum size of each sub-
From: "Steven Rostedt (Google)"
Add a self test that will write into the trace buffer with differ trace
sub buffer order sizes.
Signed-off-by: Steven Rostedt (Google)
---
.../ftrace/test.d/00basic/ringbuffer_order.tc | 95 +++
1 file changed, 95 insertions(+)
c
From: "Steven Rostedt (Google)"
Add to the documentation how to use the buffer_subbuf_order file to change
the size and how it affects what events can be added to the ring buffer.
Signed-off-by: Steven Rostedt (Google)
---
Documentation/trace/ftrace.rst | 27
From: "Steven Rostedt (Google)"
The ring_buffer_subbuf_order_set() was creating ring_buffer_per_cpu
cpu_buffers with the new subbuffers with the updated order, and if they
all successfully were created, then they the ring_buffer's per_cpu buffers
would be freed and replaced by them.
T
From: "Steven Rostedt (Google)"
When updating the order of the sub buffers for the main buffer, make sure
that if the snapshot buffer exists, that it gets its order updated as
well.
Signed-off-by: Steven Rostedt (Google)
---
kernel/trace/tr
From: "Steven Rostedt (Google)"
The function ring_buffer_subbuf_order_set() just updated the sub-buffers
to the new size, but this also changes the size of the buffer in doing so.
As the size is determined by nr_pages * subbuf_size. If the subbuf_size is
increased without decreasing th
From: "Steven Rostedt (Google)"
Because the main buffer and the snapshot buffer need to be the same for
some tracers, otherwise it will fail and disable all tracing, the tracers
need to be stopped while updating the sub buffer sizes so that the tracers
see the main and snapsh
From: "Steven Rostedt (Google)"
Now that the ring buffer specifies the size of its sub buffers, they all
need to be the same size. When doing a read, a swap is done with a spare
page. Make sure they are the same size before doing the swap, otherwise
the read will fail.
Signed-off-
From: "Steven Rostedt (Google)"
As all the subbuffer order (subbuffer sizes) must be the same throughout
the ring buffer, check the order of the buffers that are doing a CPU
buffer swap in ring_buffer_swap_cpu() to make sure they are the same.
If the are not the same, then fail to d
From: "Steven Rostedt (Google)"
On failure to allocate ring buffer pages, the pointer to the CPU buffer
pages is freed, but the pages that were allocated previously were not.
Make sure they are freed too.
Fixes: TBD ("tracing: Set new size of the ring buffer sub page")
S
race-devel/20211213094825.61876-5-tz.stoya...@gmail.com
Signed-off-by: Tzvetomir Stoyanov (VMware)
Signed-off-by: Steven Rostedt (Google)
---
kernel/trace/ring_buffer.c | 80 ++
1 file changed, 73 insertions(+), 7 deletions(-)
diff --git a/kernel/trace/ring_buffer.c b/ke
_read_page() ]
Signed-off-by: Steven Rostedt (Google)
---
include/linux/ring_buffer.h | 11 ++--
kernel/trace/ring_buffer.c | 75
kernel/trace/ring_buffer_benchmark.c | 10 ++--
kernel/trace/trace.c | 34 +++--
4 files changed, 89
mir Stoyanov (VMware)
Signed-off-by: Steven Rostedt (Google)
---
include/linux/ring_buffer.h | 4 ++
kernel/trace/ring_buffer.c | 73 +
kernel/trace/trace.c| 48
3 files changed, 125 insertions(+)
diff --git a/include/linux/ring_buff
fer.
Link:
https://lore.kernel.org/linux-trace-devel/20211213094825.61876-3-tz.stoya...@gmail.com
Signed-off-by: Tzvetomir Stoyanov (VMware)
Signed-off-by: Steven Rostedt (Google)
---
include/linux/ring_buffer.h | 2 +-
kernel/trace/ring_buffer.c | 68 +--
inux-trace-devel/20211213094825.61876-2-tz.stoya...@gmail.com
Signed-off-by: Tzvetomir Stoyanov (VMware)
Signed-off-by: Steven Rostedt (Google)
---
kernel/trace/ring_buffer.c | 60 +++---
1 file changed, 30 insertions(+), 30 deletions(-)
diff --git a/ke
Note, this has been on my todo list since the ring buffer was created back
in 2008.
Tzvetomir last worked on this in 2021 and I need to finally get it in.
His last series was:
https://lore.kernel.org/linux-trace-devel/20211213094825.61876-1-tz.stoya...@gmail.com/
With the description of:
On Tue, 19 Dec 2023 10:36:13 -0500
Steven Rostedt wrote:
> |-- interrupt event --|-- normal context event --|-- interrupt event --|
>
> ^^ ^
> || |
> ts is befo
On Tue, 19 Dec 2023 10:10:27 -0500
Steven Rostedt wrote:
> 1000 - interrupt event
> 2000 - normal context event
> 2100 - next normal context event
>
> Where we see the delta between the interrupt event and the normal context
> event was 1000. But if we just had it be d
On Tue, 19 Dec 2023 23:37:10 +0900
Masami Hiramatsu (Google) wrote:
> Yeah the above works, but my question is, do we really need this
> really slow path? I mean;
>
> > if (w == write - event length) {
> > /* Nothing interrupted between A and C */
> > /*E*/
From: "Steven Rostedt (Google)"
The check_buffer() which checks the timestamps of the ring buffer
sub-buffer page, when enabled, only checks if the adding of deltas of the
events from the last absolute timestamp or the timestamp of the sub-buffer
page adds up to the current event.
Wh
From: "Steven Rostedt (Google)"
When the ring buffer timestamp verifier triggers, it dumps the content of
the sub-buffer. But currently it only dumps the timestamps and the offset
of the data as well as the deltas. It would be even more informative if
the event data also showed the
From: "Steven Rostedt (Google)"
Each event has a 27 bit timestamp delta that is used to hold the delta
from the last event. If the time between events is greater than 2^27, then
a timestamp is added that holds a 59 bit absolute timestamp.
Until a389d86f7fd09 ("ring-buffer: Hav
From: "Steven Rostedt (Google)"
To synchronize the timestamps with the ring buffer reservation, there are
two timestamps that are saved in the buffer meta data.
1. before_stamp
2. write_stamp
When the two are equal, the write_stamp is considered valid, as in, it may
be used to
From: "Steven Rostedt (Google)"
The check_buffer() which checks the timestamps of the ring buffer
sub-buffer page, when enabled, only checks if the adding of deltas of the
events from the last absolute timestamp or the timestamp of the sub-buffer
page adds up to the current event.
Wh
On Mon, 18 Dec 2023 17:01:06 -0500
Steven Rostedt wrote:
> @@ -3347,7 +3418,8 @@ static void check_buffer(struct ring_buffer_per_cpu
> *cpu_buffer,
> }
> }
> if ((full && ts > info->ts) ||
> - (!full && ts + info->del
On Mon, 18 Dec 2023 13:42:40 -0500
Steven Rostedt wrote:
> > >
> > > > static bool rb_time_cmp_and_update(rb_time_t *t, u64 expect, u64 set)
> > > > {
> > > > - return rb_time_cmpxchg(t, expect, set);
> > > > +#ifdef RB_T
From: "Steven Rostedt (Google)"
When the ring buffer timestamp verifier triggers, it dumps the content of
the sub-buffer. But currently it only dumps the timestamps and the offset
of the data as well as the deltas. It would be even more informative if
the event data also showed the
From: "Steven Rostedt (Google)"
When the ring buffer timestamp verifier triggers, it dumps the content of
the sub-buffer. But currently it only dumps the timestamps and the offset
of the data as well as the deltas. It would be even more informative if
the event data also showed the
me_cmpxchg() to work the same for both 64-bit
and 32-bit.
- Fixed reading t->time to use local64_read() and not READ_ONCE().
Steven Rostedt (Google) (2):
ring-buffer: Replace rb_time_cmpxchg() with rb_time_cmp_and_update()
ring-buffer: Remove 32bit timestamp logic
kernel/tr
From: "Steven Rostedt (Google)"
There's only one place that performs a 64-bit cmpxchg for the timestamp
processing. The cmpxchg is only to set the write_stamp equal to the
before_stamp, and if it doesn't get set, then the next event will simply
be forced to add an absolute timesta
From: "Steven Rostedt (Google)"
Each event has a 27 bit timestamp delta that is used to hold the delta
from the last event. If the time between events is greater than 2^27, then
a timestamp is added that holds a 59 bit absolute timestamp.
Until a389d86f7fd09 ("ring-buffer: Hav
On Mon, 18 Dec 2023 10:15:31 -0500
Steven Rostedt wrote:
> Basically I broke it into:
>
> 1. Remove workaround exposure from the main logic. (this patch)
> 2. Remove the workaround. (next patch).
>
> >
> > Isn't this part actual change?
>
> This part is a
On Mon, 18 Dec 2023 11:28:17 -0500
Steven Rostedt wrote:
> > Remove all references to sub-buffer and replace them with either bpage
> > or ring_buffer_page.
The user interface should not be changed.
But what I would like to have changed (and this will come after all o
On Mon, 18 Dec 2023 15:46:18 +
Vincent Donnefort wrote:
> Previously was introduced the ability to change the ring-buffer page
> size. It also introduced the concept of sub-buffer that is, a contiguous
> virtual memory space which can now be bigger than the system page size
> (4K on most
From: "Steven Rostedt (Google)"
Normally, when the filter is enabled, a temporary buffer is created to
copy the event data into it to perform the filtering logic. If the filter
passes and the event should be recorded, then the event is copied from the
temporary buffer into the r
On Mon, 18 Dec 2023 23:24:55 +0900
Masami Hiramatsu (Google) wrote:
> On Fri, 15 Dec 2023 11:55:13 -0500
> Steven Rostedt wrote:
>
> > From: "Steven Rostedt (Google)"
> >
> > There's only one place that performs a 64-bit cmpxchg for the timestamp
>
On Sun, 17 Dec 2023 17:10:45 +0900
Masami Hiramatsu (Google) wrote:
> > >> It exposes the following details which IMHO should be hidden or
> > >> configurable in a way that allows moving to a whole new mechanism
> > >> which will have significantly different characteristics in the
> > >> future:
On Fri, 15 Dec 2023 13:25:07 -0500
Mathieu Desnoyers wrote:
>
> I am not against exposing an ABI that allows userspace to alter the
> filter behavior. I disagree on the way you plan to expose the ABI.
These are no different than the knobs for sched_debug
>
> Exposing this option as an ABI in
From 62a1de0f0f9d942934565e625a7880fd85ae216a Mon Sep 17 00:00:00 2001
From: "Steven Rostedt (Google)"
Date: Fri, 15 Dec 2023 10:26:33 -0500
Subject: [PATCH] tracing: Add filter-buffer option
Normally, when the filter is enabled, a temporary buffer is created to
copy the
From: "Steven Rostedt (Google)"
Using page order for deciding what the size of the ring buffer sub buffers
are is exposing a bit too much of the implementation. Although the sub
buffers are only allocated in orders of pages, allow the user to specify
the minimum size of each sub-
From: "Steven Rostedt (Google)"
Add a self test that will write into the trace buffer with differ trace
sub buffer order sizes.
Signed-off-by: Steven Rostedt (Google)
---
.../ftrace/test.d/00basic/ringbuffer_order.tc | 95 +++
1 file changed, 95 insertions(+)
c
From: "Steven Rostedt (Google)"
Add to the documentation how to use the buffer_subbuf_order file to change
the size and how it affects what events can be added to the ring buffer.
Signed-off-by: Steven Rostedt (Google)
---
Documentation/trace/ftrace.rst | 27
From: "Steven Rostedt (Google)"
The ring_buffer_subbuf_order_set() was creating ring_buffer_per_cpu
cpu_buffers with the new subbuffers with the updated order, and if they
all successfully were created, then they the ring_buffer's per_cpu buffers
would be freed and replaced by them.
T
From: "Steven Rostedt (Google)"
The function ring_buffer_subbuf_order_set() just updated the sub-buffers
to the new size, but this also changes the size of the buffer in doing so.
As the size is determined by nr_pages * subbuf_size. If the subbuf_size is
increased without decreasing th
From: "Steven Rostedt (Google)"
When updating the order of the sub buffers for the main buffer, make sure
that if the snapshot buffer exists, that it gets its order updated as
well.
Signed-off-by: Steven Rostedt (Google)
---
kernel/trace/tr
From: "Steven Rostedt (Google)"
Because the main buffer and the snapshot buffer need to be the same for
some tracers, otherwise it will fail and disable all tracing, the tracers
need to be stopped while updating the sub buffer sizes so that the tracers
see the main and snapsh
From: "Steven Rostedt (Google)"
Now that the ring buffer specifies the size of its sub buffers, they all
need to be the same size. When doing a read, a swap is done with a spare
page. Make sure they are the same size before doing the swap, otherwise
the read will fail.
Signed-off-
From: "Steven Rostedt (Google)"
On failure to allocate ring buffer pages, the pointer to the CPU buffer
pages is freed, but the pages that were allocated previously were not.
Make sure they are freed too.
Fixes: TBD ("tracing: Set new size of the ring buffer sub page")
S
From: "Steven Rostedt (Google)"
As all the subbuffer order (subbuffer sizes) must be the same throughout
the ring buffer, check the order of the buffers that are doing a CPU
buffer swap in ring_buffer_swap_cpu() to make sure they are the same.
If the are not the same, then fail to d
_read_page()
ring_buffer_read_page()
A new API is introduced:
ring_buffer_read_page_data()
Link:
https://lore.kernel.org/linux-trace-devel/20211213094825.61876-6-tz.stoya...@gmail.com
Signed-off-by: Tzvetomir Stoyanov (VMware)
Signed-off-by: Steven Rostedt (Google)
---
include/linux/rin
race-devel/20211213094825.61876-5-tz.stoya...@gmail.com
Signed-off-by: Tzvetomir Stoyanov (VMware)
Signed-off-by: Steven Rostedt (Google)
---
kernel/trace/ring_buffer.c | 80 ++
1 file changed, 73 insertions(+), 7 deletions(-)
diff --git a/kernel/trace/ring_buffer.c b/ke
mir Stoyanov (VMware)
Signed-off-by: Steven Rostedt (Google)
---
include/linux/ring_buffer.h | 4 ++
kernel/trace/ring_buffer.c | 73 +
kernel/trace/trace.c| 48
3 files changed, 125 insertions(+)
diff --git a/include/linux/ring_buff
fer.
Link:
https://lore.kernel.org/linux-trace-devel/20211213094825.61876-3-tz.stoya...@gmail.com
Signed-off-by: Tzvetomir Stoyanov (VMware)
Signed-off-by: Steven Rostedt (Google)
---
include/linux/ring_buffer.h | 2 +-
kernel/trace/ring_buffer.c | 68 +--
inux-trace-devel/20211213094825.61876-2-tz.stoya...@gmail.com
Signed-off-by: Tzvetomir Stoyanov (VMware)
Signed-off-by: Steven Rostedt (Google)
---
kernel/trace/ring_buffer.c | 60 +++---
1 file changed, 30 insertions(+), 30 deletions(-)
diff --git a/ke
/linux-trace.git
- I made the tests a bit more advanced. Still a smoke test, but it
now checks if the string written is the same as the string read.
Steven Rostedt (Google) (10):
ring-buffer: Clear pages on error in ring_buffer_subbuf_order_set()
failure
ring-buffer: Do no swap cpu
On Fri, 15 Dec 2023 12:24:14 -0500
Mathieu Desnoyers wrote:
> On 2023-12-15 12:04, Steven Rostedt wrote:
> > On Fri, 15 Dec 2023 10:53:39 -0500
> > Mathieu Desnoyers wrote:
> [...]
> >>
> >> So rather than stacking tons of "on/off" switches for
On Fri, 15 Dec 2023 10:53:39 -0500
Mathieu Desnoyers wrote:
>
>
> I'm not convinced that a boolean state is what you need here.
I will admit the biggest motivation for this was to allow for debugging ;-)
>
> Yes, today you are in a position where you have two options:
>
> a) use the filter
From: "Steven Rostedt (Google)"
There's only one place that performs a 64-bit cmpxchg for the timestamp
processing. The cmpxchg is only to set the write_stamp equal to the
before_stamp, and if it doesn't get set, then the next event will simply
be forced to add an absolute timesta
From: "Steven Rostedt (Google)"
Each event has a 27 bit timestamp delta that is used to hold the delta
from the last event. If the time between events is greater than 2^27, then
a timestamp is added that holds a 59 bit absolute timestamp.
Until a389d86f7fd09 ("ring-buffer: Hav
es the complex logic of that code. The
difference now is that 32-bit architectures will have to add an absolute
timestamp to an event that follows an event that suffered the race
condition.
Steven Rostedt (Google) (2):
ring-buffer: Replace rb_time_cmpxchg() with rb_time_cmp_and_update()
ring-
From: "Steven Rostedt (Google)"
Normally, when the filter is enabled, a temporary buffer is created to
copy the event data into it to perform the filtering logic. If the filter
passes and the event should be recorded, then the event is copied from the
temporary buffer into the r
From: "Steven Rostedt (Google)"
The rb_time_cmpxchg() on 32-bit architectures requires setting three
32-bit words to represent the 64-bit timestamp, with some salt for
synchronization. Those are: msb, top, and bottom
The issue is, the rb_time_cmpxchg() did not properly salt the m
From: "Steven Rostedt (Google)"
When filtering is enabled, a temporary buffer is created to place the
content of the trace event output so that the filter logic can decide
from the trace event output if the trace event should be filtered out or
not. If it is to be filtered out, t
On Fri, 15 Dec 2023 07:41:51 -0500
Steven Rostedt wrote:
> From: "Steven Rostedt (Google)"
>
> When filtering is enabled, a temporary buffer is created to place the
> content of the trace event output so that the filter logic can decide
> from the trace event output
From: "Steven Rostedt (Google)"
When filtering is enabled, a temporary buffer is created to place the
content of the trace event output so that the filter logic can decide
from the trace event output if the trace event should be filtered out or
not. If it is to be filtered out, t
On Thu, 14 Dec 2023 22:18:03 -0500
Steven Rostedt wrote:
> From: "Steven Rostedt (Google)"
>
> If an update to an event is interrupted by another event between the time
> the initial event allocated its buffer and where it wrote to the
> write_stamp, the code try to r
From: "Steven Rostedt (Google)"
If an update to an event is interrupted by another event between the time
the initial event allocated its buffer and where it wrote to the
write_stamp, the code try to reset the write stamp back to the what it had
just overwritten. It knows that it was o
From: "Steven Rostedt (Google)"
If an update to an event is interrupted by another event between the time
the initial event allocated its buffer and where it wrote to the
write_stamp, the code try to reset the write stamp back to the what it had
just overwritten. It knows that it was o
On Thu, 14 Dec 2023 12:50:29 -0800
Linus Torvalds wrote:
> > But do all archs have an implementation of cmpxchg64, even if it requires
> > disabling interrupts? If not, then I definitely cannot remove this code.
>
> We have a generic header file, so anybody who uses that would get the
>
On Thu, 14 Dec 2023 12:32:38 -0800
Linus Torvalds wrote:
> On Thu, 14 Dec 2023 at 12:30, Linus Torvalds
> wrote:
> >
> > Read my email. Don't do random x86-centric things. We have that
> >
> > #ifndef system_has_cmpxchg64
> > #define system_has_cmpxchg64() false
> > #endif
> >
> >
On Thu, 14 Dec 2023 11:44:55 -0800
Linus Torvalds wrote:
> On Thu, 14 Dec 2023 at 08:55, Steven Rostedt wrote:
> >
> > And yes, this does get called in NMI context.
>
> Not on an i486-class machine they won't. You don't have a local apic
> on those, and they won't ha
On Thu, 14 Dec 2023 15:19:11 -0500
Steven Rostedt wrote:
> For this issue of the 64bit cmpxchg, is there any config that works for any
> arch that do not have a safe 64-bit cmpxchg? At least for 486, is the
> second half of the if condition reasonable?
>
> if (IS_ENABLE
On Thu, 14 Dec 2023 11:46:55 -0800
Linus Torvalds wrote:
> On Thu, 14 Dec 2023 at 09:53, Steven Rostedt wrote:
> >
> > + /*
> > +* For architectures that can not do cmpxchg() in NMI, or require
> > +* disabling interrupts to do 64-bit c
From: "Steven Rostedt (Google)"
Each event has a 27 bit timestamp delta that is used to hold the delta
from the last event. If the time between events is greater than 2^27, then
a timestamp is added that holds a 59 bit absolute timestamp.
Until a389d86f7fd09 ("ring-buffer: Hav
On Wed, 13 Dec 2023 22:53:19 -0800
Linus Torvalds wrote:
> On Wed, 13 Dec 2023 at 18:45, Steven Rostedt wrote:
> >
> > tl;dr; The ring-buffer timestamp requires a 64-bit cmpxchg to keep the
> > timestamps in sync (only in the slow paths). I was told that 64-bit cmpxchg
From: "Steven Rostedt (Google)"
Each event has a 27 bit timestamp delta that is used to hold the delta
from the last event. If the time between events is greater than 2^27, then
a timestamp is added that holds a 59 bit absolute timestamp.
Until a389d86f7fd09 ("ring-buffer: Hav
On Wed, 13 Dec 2023 21:11:26 -0500
Steven Rostedt wrote:
> @@ -3720,6 +3517,7 @@ rb_reserve_next_event(struct trace_buffer *buffer,
> struct rb_event_info info;
> int nr_loops = 0;
> int add_ts_default;
> + static int once;
>
> /* ring buffer do
hould just say "screw it" and nuke it now?
Or do you think it's worth keeping for some other architecture that 3
32-bit cmpxchgs are still faster than a single 64-bit one?
Thanks,
-- Steve
On Wed, 13 Dec 2023 21:11:26 -0500
Steven Rostedt wrote:
> From: "Steven Rostedt (G
From: "Steven Rostedt (Google)"
Each event has a 27 bit timestamp delta that is used to hold the delta
from the last event. If the time between events is greater than 2^27, then
a timestamp is added that holds a 59 bit absolute timestamp.
Until a389d86f7fd09 ("ring-buffer: Hav
From: "Steven Rostedt (Google)"
As the ring buffer recording requires cmpxchg() to work, if the
architecture does not support cmpxchg in NMI, then do not do any recording
within an NMI.
Signed-off-by: Steven Rostedt (Google)
---
kernel/trace/ring_buffer.c | 6 ++
1 file
the implemantion is.
- I rebased on top of trace/core in the:
git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace.git
- I made the tests a bit more advanced. Still a smoke test, but it
now checks if the string written is the same as the string read.
Steven Rostedt (Google)
race-devel/20211213094825.61876-5-tz.stoya...@gmail.com
Signed-off-by: Tzvetomir Stoyanov (VMware)
Signed-off-by: Steven Rostedt (Google)
---
kernel/trace/ring_buffer.c | 80 ++
1 file changed, 73 insertions(+), 7 deletions(-)
diff --git a/kernel/trace/ring_buffer.c b/ke
From: "Steven Rostedt (Google)"
Add a self test that will write into the trace buffer with differ trace
sub buffer order sizes.
Signed-off-by: Steven Rostedt (Google)
---
.../ftrace/test.d/00basic/ringbuffer_order.tc | 95 +++
1 file changed, 95 insertions(+)
c
_read_page()
ring_buffer_read_page()
A new API is introduced:
ring_buffer_read_page_data()
Link:
https://lore.kernel.org/linux-trace-devel/20211213094825.61876-6-tz.stoya...@gmail.com
Signed-off-by: Tzvetomir Stoyanov (VMware)
Signed-off-by: Steven Rostedt (Google)
---
include/linux/rin
From: "Steven Rostedt (Google)"
Using page order for deciding what the size of the ring buffer sub buffers
are is exposing a bit too much of the implementation. Although the sub
buffers are only allocated in orders of pages, allow the user to specify
the minimum size of each sub-
From: "Steven Rostedt (Google)"
When updating the order of the sub buffers for the main buffer, make sure
that if the snapshot buffer exists, that it gets its order updated as
well.
Signed-off-by: Steven Rostedt (Google)
---
kernel/trace/tr
mir Stoyanov (VMware)
Signed-off-by: Steven Rostedt (Google)
---
include/linux/ring_buffer.h | 4 ++
kernel/trace/ring_buffer.c | 73 +
kernel/trace/trace.c| 48
3 files changed, 125 insertions(+)
diff --git a/include/linux/ring_buff
From: "Steven Rostedt (Google)"
Now that the ring buffer specifies the size of its sub buffers, they all
need to be the same size. When doing a read, a swap is done with a spare
page. Make sure they are the same size before doing the swap, otherwise
the read will fail.
Signed-off-
From: "Steven Rostedt (Google)"
Because the main buffer and the snapshot buffer need to be the same for
some tracers, otherwise it will fail and disable all tracing, the tracers
need to be stopped while updating the sub buffer sizes so that the tracers
see the main and snapsh
From: "Steven Rostedt (Google)"
The ring_buffer_subbuf_order_set() was creating ring_buffer_per_cpu
cpu_buffers with the new subbuffers with the updated order, and if they
all successfully were created, then they the ring_buffer's per_cpu buffers
would be freed and replaced by them.
T
From: "Steven Rostedt (Google)"
The function ring_buffer_subbuf_order_set() just updated the sub-buffers
to the new size, but this also changes the size of the buffer in doing so.
As the size is determined by nr_pages * subbuf_size. If the subbuf_size is
increased without decreasing th
fer.
Link:
https://lore.kernel.org/linux-trace-devel/20211213094825.61876-3-tz.stoya...@gmail.com
Signed-off-by: Tzvetomir Stoyanov (VMware)
Signed-off-by: Steven Rostedt (Google)
---
include/linux/ring_buffer.h | 2 +-
kernel/trace/ring_buffer.c | 68 +--
From: "Steven Rostedt (Google)"
Add to the documentation how to use the buffer_subbuf_order file to change
the size and how it affects what events can be added to the ring buffer.
Signed-off-by: Steven Rostedt (Google)
---
Documentation/trace/ftrace.rst | 27
From: "Steven Rostedt (Google)"
As all the subbuffer order (subbuffer sizes) must be the same throughout
the ring buffer, check the order of the buffers that are doing a CPU
buffer swap in ring_buffer_swap_cpu() to make sure they are the same.
If the are not the same, then fail to d
From: "Steven Rostedt (Google)"
On failure to allocate ring buffer pages, the pointer to the CPU buffer
pages is freed, but the pages that were allocated previously were not.
Make sure they are freed too.
Fixes: TBD ("tracing: Set new size of the ring buffer sub page")
S
inux-trace-devel/20211213094825.61876-2-tz.stoya...@gmail.com
Signed-off-by: Tzvetomir Stoyanov (VMware)
Signed-off-by: Steven Rostedt (Google)
---
kernel/trace/ring_buffer.c | 60 +++---
1 file changed, 30 insertions(+), 30 deletions(-)
diff --git a/ke
From: "Steven Rostedt (Google)"
There's no reason to give an arbitrary limit to the size of a raw trace
marker. Just let it be as big as the size that is allowed by the ring
buffer itself.
And there's also no reason to artificially break up the write to
TRACE_BUF_SIZE, as that's not
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