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Date: Fri, 25 Mar 2011 12:00:13 +0100
From: Robert Richter <robert.richter@....com>
To: Heinz Graalfs <graalfs@...ux.vnet.ibm.com>
CC: "mingo@...e.hu" <mingo@...e.hu>,
"oprofile-list@...ts.sf.net" <oprofile-list@...ts.sf.net>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"linux-s390@...r.kernel.org" <linux-s390@...r.kernel.org>,
"borntraeger@...ibm.com" <borntraeger@...ibm.com>,
"schwidefsky@...ibm.com" <schwidefsky@...ibm.com>,
"heiko.carstens@...ibm.com" <heiko.carstens@...ibm.com>,
Mahesh Salgaonkar <mahesh@...ux.vnet.ibm.com>,
Maran Pakkirisamy <maranp@...ux.vnet.ibm.com>
Subject: Re: [patch v2 1/3] This patch adds support for hardware based
sampling on System z processors (models z10 and up)
On 21.01.11 05:06:52, Heinz Graalfs wrote:
> From: Heinz Graalfs <graalfs@...ux.vnet.ibm.com>
>
> System z's hardware sampling is described in detail in:
>
> SA23-2260-01 "The Load-Program-Parameter and CPU-Measurement Facilities"
>
> The patch introduces
> - support for System z's hardware sampler in OProfile's kernel module
> - it adds functions that control all hardware sampling related operations as
> - checking if hardware sampling feature is available
> - ie: on System z models z10 and up, in LPAR mode only, and authorised during LPAR activation
> - allocating memory for the hardware sampling feature
> - starting/stopping hardware sampling
>
> All functions required to start and stop hardware sampling have to be
> invoked by the oprofile kernel module as provided by the other patches of this patch set.
>
> In case hardware based sampling cannot be setup standard timer based sampling is used by OProfile.
>
> Signed-off-by: Mahesh Salgaonkar <mahesh@...ux.vnet.ibm.com>
> Signed-off-by: Maran Pakkirisamy <maranp@...ux.vnet.ibm.com>
> Signed-off-by: Heinz Graalfs <graalfs@...ux.vnet.ibm.com>
> ---
> arch/Kconfig | 3
> arch/s390/Kconfig | 1
> arch/s390/oprofile/hwsampler.c | 1256 +++++++++++++++++++++++++++++++++++++++++
> arch/s390/oprofile/hwsampler.h | 113 +++
> 4 files changed, 1373 insertions(+)
> +int hwsampler_setup()
> +{
> + int rc;
> + int cpu;
> + struct hws_cpu_buffer *cb;
> +
> + mutex_lock(&hws_sem);
> +
> + rc = -EINVAL;
> + if (hws_state)
> + goto setup_exit;
> +
> + hws_state = HWS_INIT;
hws_state is never set to zero again, so we will pass this point only
one time, even after hwsampler_shutdown(). Is this intended? Only
loading and unloading this as module would work.
Maybe we clear hws_state in hwsampler_shutdown()?
-Robert
> +
> + init_all_cpu_buffers();
> +
> + rc = check_hardware_prerequisites();
> + if (rc)
> + goto setup_exit;
> +
> + rc = check_qsi_on_setup();
> + if (rc)
> + goto setup_exit;
> +
> + rc = -EINVAL;
> + hws_wq = create_workqueue("hwsampler");
> + if (!hws_wq)
> + goto setup_exit;
> +
> + register_cpu_notifier(&hws_cpu_notifier);
> +
> + for_each_online_cpu(cpu) {
> + cb = &per_cpu(sampler_cpu_buffer, cpu);
> + INIT_WORK(&cb->worker, worker);
> + rc = smp_ctl_qsi(cpu);
> + WARN_ON(rc);
> + if (min_sampler_rate != cb->qsi.min_sampl_rate) {
> + if (min_sampler_rate) {
> + printk(KERN_WARNING
> + "hwsampler: different min sampler rate values.\n");
> + if (min_sampler_rate < cb->qsi.min_sampl_rate)
> + min_sampler_rate =
> + cb->qsi.min_sampl_rate;
> + } else
> + min_sampler_rate = cb->qsi.min_sampl_rate;
> + }
> + if (max_sampler_rate != cb->qsi.max_sampl_rate) {
> + if (max_sampler_rate) {
> + printk(KERN_WARNING
> + "hwsampler: different max sampler rate values.\n");
> + if (max_sampler_rate > cb->qsi.max_sampl_rate)
> + max_sampler_rate =
> + cb->qsi.max_sampl_rate;
> + } else
> + max_sampler_rate = cb->qsi.max_sampl_rate;
> + }
> + }
> + register_external_interrupt(0x1407, hws_ext_handler);
> +
> + hws_state = HWS_DEALLOCATED;
> + rc = 0;
> +
> +setup_exit:
> + mutex_unlock(&hws_sem);
> + return rc;
> +}
> +
> +int hwsampler_shutdown()
> +{
> + int rc;
> +
> + mutex_lock(&hws_sem);
> +
> + rc = -EINVAL;
> + if (hws_state == HWS_DEALLOCATED || hws_state == HWS_STOPPED) {
> + mutex_unlock(&hws_sem);
> +
> + if (hws_wq)
> + flush_workqueue(hws_wq);
> +
> + mutex_lock(&hws_sem);
> +
> + if (hws_state == HWS_STOPPED) {
> + smp_ctl_clear_bit(0, 5); /* set bit 58 CR0 off */
> + deallocate_sdbt();
> + }
> + if (hws_wq) {
> + destroy_workqueue(hws_wq);
> + hws_wq = NULL;
> + }
> +
> + unregister_external_interrupt(0x1407, hws_ext_handler);
> + hws_state = HWS_INIT;
> + rc = 0;
> + }
> + mutex_unlock(&hws_sem);
> +
> + unregister_cpu_notifier(&hws_cpu_notifier);
> +
> + return rc;
> +}
--
Advanced Micro Devices, Inc.
Operating System Research Center
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