On Thu, 18 Apr 2024 12:10:59 +0100
Jonthan Haslam wrote:
> Hi Masami,
>
> > > > OK, then I'll push this to for-next at this moment.
> > > > Please share if you have a good idea for the batch interface which can
> > > > be
> > > > backported. I guess it should involve updating userspace changes
Hi Masami,
> > > OK, then I'll push this to for-next at this moment.
> > > Please share if you have a good idea for the batch interface which can be
> > > backported. I guess it should involve updating userspace changes too.
> >
> > Did you (or anyone else) need anything more from me on this one
> > > OK, then I'll push this to for-next at this moment.
> > > Please share if you have a good idea for the batch interface which can be
> > > backported. I guess it should involve updating userspace changes too.
> >
> > Did you (or anyone else) need anything more from me on this one so that it
On Wed, 10 Apr 2024 11:38:11 +0100
Jonthan Haslam wrote:
> Hi Masami,
>
> > > > Which is why I was asking to land this patch as is, as it relieves the
> > > > scalability pains in production and is easy to backport to old
> > > > kernels. And then we can work on batched APIs and switch to
Hi Masami,
> > > Which is why I was asking to land this patch as is, as it relieves the
> > > scalability pains in production and is easy to backport to old
> > > kernels. And then we can work on batched APIs and switch to per-CPU rw
> > > semaphore.
>
> OK, then I'll push this to for-next at
> > Things to note about the results:
> >
> > - The results are slightly variable so don't get too caught up on
> > individual thread count - it's the trend that is important.
> > - In terms of throughput with this specific benchmark a *very* macro view
> > is that the RW spinlock provides
On Wed, Apr 3, 2024 at 4:05 AM Jonthan Haslam wrote:
>
> > > > > Given the discussion around per-cpu rw semaphore and need for
> > > > > (internal) batched attachment API for uprobes, do you think you can
> > > > > apply this patch as is for now? We can then gain initial improvements
> > > > > in
> > > > Given the discussion around per-cpu rw semaphore and need for
> > > > (internal) batched attachment API for uprobes, do you think you can
> > > > apply this patch as is for now? We can then gain initial improvements
> > > > in scalability that are also easy to backport, and Jonathan will
On Fri, Mar 29, 2024 at 5:36 PM Masami Hiramatsu wrote:
>
> On Fri, 29 Mar 2024 10:33:57 -0700
> Andrii Nakryiko wrote:
>
> > On Wed, Mar 27, 2024 at 5:45 PM Andrii Nakryiko
> > wrote:
> > >
> > > On Wed, Mar 27, 2024 at 5:18 PM Masami Hiramatsu
> > > wrote:
> > > >
> > > > On Wed, 27 Mar
On Fri, 29 Mar 2024 10:33:57 -0700
Andrii Nakryiko wrote:
> On Wed, Mar 27, 2024 at 5:45 PM Andrii Nakryiko
> wrote:
> >
> > On Wed, Mar 27, 2024 at 5:18 PM Masami Hiramatsu
> > wrote:
> > >
> > > On Wed, 27 Mar 2024 17:06:01 +
> > > Jonthan Haslam wrote:
> > >
> > > > > > Masami,
> > >
On Wed, Mar 27, 2024 at 5:45 PM Andrii Nakryiko
wrote:
>
> On Wed, Mar 27, 2024 at 5:18 PM Masami Hiramatsu wrote:
> >
> > On Wed, 27 Mar 2024 17:06:01 +
> > Jonthan Haslam wrote:
> >
> > > > > Masami,
> > > > >
> > > > > Given the discussion around per-cpu rw semaphore and need for
> > > >
On Wed, Mar 27, 2024 at 5:18 PM Masami Hiramatsu wrote:
>
> On Wed, 27 Mar 2024 17:06:01 +
> Jonthan Haslam wrote:
>
> > > > Masami,
> > > >
> > > > Given the discussion around per-cpu rw semaphore and need for
> > > > (internal) batched attachment API for uprobes, do you think you can
> > >
On Wed, 27 Mar 2024 17:06:01 +
Jonthan Haslam wrote:
> > > Masami,
> > >
> > > Given the discussion around per-cpu rw semaphore and need for
> > > (internal) batched attachment API for uprobes, do you think you can
> > > apply this patch as is for now? We can then gain initial improvements
> > Masami,
> >
> > Given the discussion around per-cpu rw semaphore and need for
> > (internal) batched attachment API for uprobes, do you think you can
> > apply this patch as is for now? We can then gain initial improvements
> > in scalability that are also easy to backport, and Jonathan will
On Mon, 25 Mar 2024 19:04:59 +
Jonthan Haslam wrote:
> Hi Masami,
>
> > > This change has been tested against production workloads that exhibit
> > > significant contention on the spinlock and an almost order of magnitude
> > > reduction for mean uprobe execution time is observed (28 -> 3.5
On Tue, 26 Mar 2024 09:01:47 -0700
Andrii Nakryiko wrote:
> On Sun, Mar 24, 2024 at 8:03 PM Masami Hiramatsu wrote:
> >
> > On Thu, 21 Mar 2024 07:57:35 -0700
> > Jonathan Haslam wrote:
> >
> > > Active uprobes are stored in an RB tree and accesses to this tree are
> > > dominated by read
On Sun, Mar 24, 2024 at 8:03 PM Masami Hiramatsu wrote:
>
> On Thu, 21 Mar 2024 07:57:35 -0700
> Jonathan Haslam wrote:
>
> > Active uprobes are stored in an RB tree and accesses to this tree are
> > dominated by read operations. Currently these accesses are serialized by
> > a spinlock but this
> > > Have you considered/measured per-CPU RW semaphores?
> >
> > No I hadn't but thanks hugely for suggesting it! In initial measurements
> > it seems to be between 20-100% faster than the RW spinlocks! Apologies for
> > all the exclamation marks but I'm very excited. I'll do some more testing
>
On Mon, Mar 25, 2024 at 12:12 PM Jonthan Haslam
wrote:
>
> Hi Ingo,
>
> > > This change has been tested against production workloads that exhibit
> > > significant contention on the spinlock and an almost order of magnitude
> > > reduction for mean uprobe execution time is observed (28 -> 3.5
>
Hi Ingo,
> > This change has been tested against production workloads that exhibit
> > significant contention on the spinlock and an almost order of magnitude
> > reduction for mean uprobe execution time is observed (28 -> 3.5 microsecs).
>
> Have you considered/measured per-CPU RW semaphores?
Hi Masami,
> > This change has been tested against production workloads that exhibit
> > significant contention on the spinlock and an almost order of magnitude
> > reduction for mean uprobe execution time is observed (28 -> 3.5 microsecs).
>
> Looks good to me.
>
> Acked-by: Masami Hiramatsu
On Thu, 21 Mar 2024 07:57:35 -0700
Jonathan Haslam wrote:
> Active uprobes are stored in an RB tree and accesses to this tree are
> dominated by read operations. Currently these accesses are serialized by
> a spinlock but this leads to enormous contention when large numbers of
> threads are
* Jonathan Haslam wrote:
> Active uprobes are stored in an RB tree and accesses to this tree are
> dominated by read operations. Currently these accesses are serialized by
> a spinlock but this leads to enormous contention when large numbers of
> threads are executing active probes.
>
> This
On Thu, Mar 21, 2024 at 7:57 AM Jonathan Haslam
wrote:
>
> Active uprobes are stored in an RB tree and accesses to this tree are
> dominated by read operations. Currently these accesses are serialized by
> a spinlock but this leads to enormous contention when large numbers of
> threads are
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