From: Peter Zijlstra <peterz@infradead.org>
To: Juergen Gross <jgross@suse.com>
Cc: linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org,
paulmck@kernel.org, mhocko@suse.com,
Jonathan Corbet <corbet@lwn.net>
Subject: Re: [PATCH 3/3] kernel/smp: add more data to CSD lock debugging
Date: Fri, 26 Feb 2021 17:38:44 +0100 [thread overview]
Message-ID: <YDkkFBerBlW5uUBS@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20210226112521.8641-4-jgross@suse.com>
I hate all of this, but if this will finally catch the actual problem,
we can then revert all this, so sure.
Also, I think this will conflict with the patches from Nadav that I have
queued:
https://lkml.kernel.org/r/20210220231712.2475218-1-namit@vmware.com
which I'll be pushing to tip/x86/mm once -rc1 happens.
On Fri, Feb 26, 2021 at 12:25:21PM +0100, Juergen Gross wrote:
> +static void __smp_call_single_queue_debug(int cpu, struct llist_node *node)
> +{
> + unsigned int this_cpu = smp_processor_id();
> + struct cfd_seq_local *seq = this_cpu_ptr(&cfd_seq_local);
> + struct call_function_data *cfd = this_cpu_ptr(&cfd_data);
> + struct cfd_percpu *pcpu = per_cpu_ptr(cfd->pcpu, cpu);
> +
> + cfd_seq_store(pcpu->seq_queue, this_cpu, cpu, CFD_SEQ_QUEUE);
> + if (llist_add(node, &per_cpu(call_single_queue, cpu))) {
> + cfd_seq_store(pcpu->seq_ipi, this_cpu, cpu, CFD_SEQ_IPI);
> + cfd_seq_store(seq->ping, this_cpu, cpu, CFD_SEQ_PING);
> + send_call_function_single_ipi(cpu);
> + cfd_seq_store(seq->pinged, this_cpu, cpu, CFD_SEQ_PINGED);
> + } else {
> + cfd_seq_store(pcpu->seq_noipi, this_cpu, cpu, CFD_SEQ_NOIPI);
> + }
> +}
> #else
> +#define cfd_seq_store(var, src, dst, type)
> +
> static void csd_lock_record(call_single_data_t *csd)
> {
> }
> @@ -290,6 +396,19 @@ static DEFINE_PER_CPU_SHARED_ALIGNED(call_single_data_t, csd_data);
>
> void __smp_call_single_queue(int cpu, struct llist_node *node)
> {
> +#ifdef CONFIG_CSD_LOCK_WAIT_DEBUG
> + if (static_branch_unlikely(&csdlock_debug_extended)) {
> + unsigned int type;
> +
> + type = CSD_TYPE(container_of(node, call_single_data_t,
> + node.llist));
> + if (type == CSD_TYPE_SYNC || type == CSD_TYPE_ASYNC) {
> + __smp_call_single_queue_debug(cpu, node);
> + return;
> + }
> + }
> +#endif
This is a bit weird, might as well put it in generic_exec_single()
because there you still know the type matches.
> @@ -712,12 +840,21 @@ static void smp_call_function_many_cond(const struct cpumask *mask,
> csd->node.src = smp_processor_id();
> csd->node.dst = cpu;
> #endif
> - if (llist_add(&csd->node.llist, &per_cpu(call_single_queue, cpu)))
> + cfd_seq_store(pcpu->seq_queue, this_cpu, cpu, CFD_SEQ_QUEUE);
> + if (llist_add(&csd->node.llist, &per_cpu(call_single_queue, cpu))) {
> __cpumask_set_cpu(cpu, cfd->cpumask_ipi);
> + cfd_seq_store(pcpu->seq_ipi, this_cpu, cpu, CFD_SEQ_IPI);
> + } else {
> + cfd_seq_store(pcpu->seq_noipi, this_cpu, cpu, CFD_SEQ_NOIPI);
> + }
> }
>
> /* Send a message to all CPUs in the map */
> + cfd_seq_store(this_cpu_ptr(&cfd_seq_local)->ping, this_cpu,
> + CFD_SEQ_NOCPU, CFD_SEQ_PING);
> arch_send_call_function_ipi_mask(cfd->cpumask_ipi);
> + cfd_seq_store(this_cpu_ptr(&cfd_seq_local)->pinged, this_cpu,
> + CFD_SEQ_NOCPU, CFD_SEQ_PINGED);
Too bad we can't share with the single case, a well.
next prev parent reply other threads:[~2021-02-26 16:40 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-26 11:25 [PATCH 0/3] kernel/smp.c: add more CSD lock debugging Juergen Gross
2021-02-26 11:25 ` [PATCH 1/3] kernel/smp: add boot parameter for controlling " Juergen Gross
2021-02-26 11:25 ` [PATCH 2/3] kernel/smp: prepare more " Juergen Gross
2021-02-26 11:25 ` [PATCH 3/3] kernel/smp: add more data to " Juergen Gross
2021-02-26 16:38 ` Peter Zijlstra [this message]
2021-02-26 18:12 ` Paul E. McKenney
2021-02-26 21:05 ` Peter Zijlstra
2021-03-01 0:07 ` Paul E. McKenney
2021-03-01 15:45 ` Peter Zijlstra
2021-03-01 15:53 ` Jürgen Groß
2021-03-01 16:45 ` Paul E. McKenney
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=YDkkFBerBlW5uUBS@hirez.programming.kicks-ass.net \
--to=peterz@infradead.org \
--cc=corbet@lwn.net \
--cc=jgross@suse.com \
--cc=linux-doc@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mhocko@suse.com \
--cc=paulmck@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).