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Date: Wed, 19 Jan 2011 17:54:44 +0100
From: Heinz Graalfs <graalfs@...ux.vnet.ibm.com>
To: Robert Richter <robert.richter@....com>
Cc: "mingo@...e.hu" <mingo@...e.hu>,
"oprofile-list@...ts.sf.net" <oprofile-list@...ts.sf.net>,
"linux-s390@...r.kernel.org" <linux-s390@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"heiko.carstens@...ibm.com" <heiko.carstens@...ibm.com>,
Mahesh Salgaonkar <mahesh@...ux.vnet.ibm.com>,
"schwidefsky@...ibm.com" <schwidefsky@...ibm.com>,
Maran Pakkirisamy <maranp@...ux.vnet.ibm.com>,
"borntraeger@...ibm.com" <borntraeger@...ibm.com>
Subject: Re: [patch 1/4] This patch adds support for hardware based
sampling on System z processors (models z10 and up)
Hello Robert,
please find below (and in the following 2 mails) my answers to your
comments.
The patch-set will follow soon.
Heinz
On Mon, 2011-01-03 at 18:06 +0100, Robert Richter wrote:
> On 20.12.10 08:05:42, graalfs@...ux.vnet.ibm.com wrote:
> > From: graalfs@...ux.vnet.ibm.com
>
> This should include the real name like in your Signed-off-by tag.
>
> You can fix this by reconfiguring git and recommitting your patches
> (git rebase -i ..., git commit --amend --reset-author).
>
> >
> > The CPU Measurement Facility CPUMF is described in the z/Architecture Principles of Operation.
> >
> > The patch introduces
> > - a new configuration option OPROFILE_HWSAMPLING_MODE
> > - a new kernel module hwsampler that controls 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
> > The hwsampler module will also depend on CONFIG_OPROFILE and CONFIG_64BIT.
> >
> > 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/s390/Kconfig | 22
> > arch/s390/include/asm/hwsampler.h | 130 +++
> > arch/s390/oprofile/Makefile | 6
> > drivers/s390/hwsampler/hwsampler-main.c | 1155 ++++++++++++++++++++++++++++++++
> > drivers/s390/hwsampler/smpctl.c | 170 ++++
>
> Is there a reason for splitting the code into two files? If we would
> merge hwsampler-main.c and smpctl.c we could make a lot functions
> static which simplifies the interface. We could also drop the
> hwsampler/ directory and put all in drivers/s390/hwsampler.c.
I merged smpctl.c contents into new hwsampler.c, hwsampler.c is now
located in arch/s390/oprofile.
As you proposed I integrated everything in the oprofile kernel module.
>
> Another thing is, wouldn't all of this better be part of cpu
> initialization code? This is not really a driver, it only registers a
> cpu notifier. Do you need to build this as module? I leave this
> decision to the s390 maintainers.
>
> > 5 files changed, 1483 insertions(+)
> >
> > Index: linux-2.6/arch/s390/include/asm/hwsampler.h
> > ===================================================================
> > --- /dev/null
> > +++ linux-2.6/arch/s390/include/asm/hwsampler.h
>
> This file should only contain definitions for the public interface.
> All structs should be private, defined in something like
>
> drivers/s390/hwsampler.h
I moved the structs to drivers/s390/hwsampler.h
>
> or so. All of them are only used in hwsampler-main.c or smpctl.c.
>
> To avoid namespace collisions, add a prefix like hws_ to all symbols.
>
OK, done
> > @@ -0,0 +1,130 @@
> > +/*
> > + * CPUMF HW sampler structures and prototypes
> > + *
> > + * Copyright IBM Corp. 2010
> > + * Author(s): Heinz Graalfs <graalfs@...ibm.com>
> > + */
> > +
> > +#ifndef HWSAMPLER_H_
> > +#define HWSAMPLER_H_
> > +
> > +#include <linux/workqueue.h>
> > +
> > +struct qsi_info_block /* QUERY SAMPLING information block */
> > +{ /* Bit(s) */
> > + unsigned int b0_13:14; /* 0-13: zeros */
> > + unsigned int as:1; /* 14: sampling authorisation control*/
> > + unsigned int b15_21:7; /* 15-21: zeros */
> > + unsigned int es:1; /* 22: sampling enable control */
> > + unsigned int b23_29:7; /* 23-29: zeros */
> > + unsigned int cs:1; /* 30: sampling activation control */
> > + unsigned int:1; /* 31: reserved */
> > + unsigned int bsdes:16; /* 4-5: size of sampling entry */
> > + unsigned int:16; /* 6-7: reserved */
> > + unsigned long min_sampl_rate; /* 8-15: minimum sampling interval */
> > + unsigned long max_sampl_rate; /* 16-23: maximum sampling interval*/
> > + unsigned long tear; /* 24-31: TEAR contents */
> > + unsigned long dear; /* 32-39: DEAR contents */
> > + unsigned int rsvrd0; /* 40-43: reserved */
> > + unsigned int cpu_speed; /* 44-47: CPU speed */
> > + unsigned long long rsvrd1; /* 48-55: reserved */
> > + unsigned long long rsvrd2; /* 56-63: reserved */
> > +};
> > +
> > +struct ssctl_request_block /* SET SAMPLING CONTROLS req block */
> > +{ /* bytes 0 - 7 Bit(s) */
> > + unsigned int s:1; /* 0: maximum buffer indicator */
> > + unsigned int h:1; /* 1: part. level reserved for VM use*/
> > + unsigned long b2_53:52; /* 2-53: zeros */
> > + unsigned int es:1; /* 54: sampling enable control */
> > + unsigned int b55_61:7; /* 55-61: - zeros */
> > + unsigned int cs:1; /* 62: sampling activation control */
> > + unsigned int b63:1; /* 63: zero */
> > + unsigned long interval; /* 8-15: sampling interval */
> > + unsigned long tear; /* 16-23: TEAR contents */
> > + unsigned long dear; /* 24-31: DEAR contents */
> > + /* 32-63: */
> > + unsigned long rsvrd1; /* reserved */
> > + unsigned long rsvrd2; /* reserved */
> > + unsigned long rsvrd3; /* reserved */
> > + unsigned long rsvrd4; /* reserved */
> > +};
> > +
> > +typedef void oprf_add_sample_func(unsigned long pc,
> > + struct pt_regs * const regs,
> > + unsigned long event, int is_kernel,
> > + struct task_struct *task);
>
> Don't use typedefs.
OK, done
>
> > +
> > +struct cpu_buffer {
> > + unsigned long first_sdbt; /* @ of 1st SDB-Table for this CP*/
> > + unsigned long worker_entry;
> > + unsigned long sample_overflow; /* taken from SDB ... */
> > + struct qsi_info_block qsi;
> > + struct ssctl_request_block ssctl;
> > + struct work_struct worker;
> > + oprf_add_sample_func *add_sample_f;
> > + atomic_t ext_params;
> > + unsigned long req_alert;
> > + unsigned long loss_of_sample_data;
> > + unsigned long invalid_entry_address;
> > + unsigned long incorrect_sdbt_entry;
> > + unsigned long sample_auth_change_alert;
> > + unsigned int finish:1;
> > + unsigned int oom:1;
> > + unsigned int stop_mode:1;
> > +};
> > +
> > +struct data_entry {
> > + unsigned int def:16; /* 0-15 Data Entry Format */
> > + unsigned int R:4; /* 16-19 reserved */
> > + unsigned int U:4; /* 20-23 Number of unique instruct. */
> > + unsigned int z:2; /* zeros */
> > + unsigned int T:1; /* 26 PSW DAT mode */
> > + unsigned int W:1; /* 27 PSW wait state */
> > + unsigned int P:1; /* 28 PSW Problem state */
> > + unsigned int AS:2; /* 29-30 PSW address-space control */
> > + unsigned int I:1; /* 31 entry valid or invalid */
> > + unsigned int:16;
> > + unsigned int prim_asn:16; /* primary ASN */
> > + unsigned long long ia; /* Instruction Address */
> > + unsigned long long lpp; /* Logical-Partition Program Param. */
> > + unsigned long long vpp; /* Virtual-Machine Program Param. */
> > +};
> > +
> > +struct trailer_entry {
> > + unsigned int f:1; /* 0 - Block Full Indicator */
> > + unsigned int a:1; /* 1 - Alert request control */
> > + unsigned long:62; /* 2 - 63: Reserved */
> > + unsigned long overflow; /* 64 - sample Overflow count */
> > + unsigned long timestamp; /* 16 - time-stamp */
> > + unsigned long timestamp1; /* */
> > + unsigned long reserved1; /* 32 -Reserved */
> > + unsigned long reserved2; /* */
> > + unsigned long progusage1; /* 48 - reserved for programming use */
> > + unsigned long progusage2; /* */
> > +};
> > +
> > +int hwsampler_setup(void);
> > +int hwsampler_shutdown(void);
> > +int hwsampler_allocate(unsigned long sdbt, unsigned long sdb);
> > +int hwsampler_deallocate(void);
> > +long hwsampler_query_min_interval(void);
> > +long hwsampler_query_max_interval(void);
> > +int hwsampler_start_all(unsigned long interval);
> > +int hwsampler_stop_all(void);
> > +int hwsampler_deactivate(unsigned int cpu);
> > +int hwsampler_activate(unsigned int cpu);
> > +unsigned long hwsampler_get_sample_overflow_count(unsigned int cpu);
> > +
>
> All the following functions should have a prefix (e.g. hws_):
all smp_ functions are now static in hwsampler.c
>
> > +int smp_ctl_qsi(int);
> > +int smp_ctl_ssctl_deactivate(int);
> > +int smp_ctl_ssctl_stop(int);
> > +int smp_ctl_ssctl_enable_activate(int, unsigned long);
> > +
> > +int qsi(void *);
> > +
> > +void execute_qsi(void *);
> > +void execute_ssctl(void *);
>
> Many functions above are for internal use only, these should be
> removed from this interface and made static.
>
all structs moved to arch/s390/oprofile/hwsampler.h
> > +
> > +#endif /*HWSAMPLER_H_*/
> > +
> > Index: linux-2.6/drivers/s390/hwsampler/hwsampler-main.c
> > ===================================================================
> > --- /dev/null
> > +++ linux-2.6/drivers/s390/hwsampler/hwsampler-main.c
>
> > +static int __cpuinit hws_cpu_callback(struct notifier_block *nfb,
> > + unsigned long action, void *hcpu)
> > +{
> > + /* We do not have sampler space available for all possible CPUs.
> > + All CPUs should be online when hw sampling is activated. */
> > + return NOTIFY_BAD;
>
> Is this to prevent bringing cpus on-/offline?
yes, we don't allow cpu varyon/off during hardware sampling
>
> > +}
>
> [...]
>
> > +static int __init hwsampler_init(void)
> > +{
> > + hws_state = HWS_INIT;
> > + register_cpu_notifier(&hws_cpu_notifier);
> > + return 0;
> > +}
> > +
> > +static void __exit hwsampler_exit(void)
> > +{
> > + unregister_cpu_notifier(&hws_cpu_notifier);
> > +}
> > +
> > +module_init(hwsampler_init);
> > +module_exit(hwsampler_exit);
> > +
> > +MODULE_LICENSE("GPL");
> > +MODULE_AUTHOR("Heinz Graalfs <graalfs@...ibm.com>");
> > +MODULE_DESCRIPTION("IBM CPUMF Customer Mode Sampling Kernel Module");
>
> [...]
>
> > Index: linux-2.6/arch/s390/Kconfig
> > ===================================================================
> > --- linux-2.6.orig/arch/s390/Kconfig
> > +++ linux-2.6/arch/s390/Kconfig
> > @@ -127,6 +127,7 @@ config S390
> > select ARCH_INLINE_WRITE_UNLOCK_BH
> > select ARCH_INLINE_WRITE_UNLOCK_IRQ
> > select ARCH_INLINE_WRITE_UNLOCK_IRQRESTORE
> > + select HAVE_HWSAMPLER
> >
> > config SCHED_OMIT_FRAME_POINTER
> > bool
> > @@ -618,6 +619,27 @@ config SECCOMP
> >
> > If unsure, say Y.
> >
> > +config HWSAMPLER
> > + tristate "Exploit CPUMF hardware sampling with OProfile"
> > + depends on OPROFILE
> > + depends on HAVE_HWSAMPLER
> > + depends on 64BIT
> > + select OPROFILE_HWSAMPLING_MODE
> > + help
> > + Hardware (HW) sampling is a feature provided by z processor.
> > + The sampling process is implemented in hardware and millicode
> > + and thus does not affect the operating system being observed,
> > + apart from the required buffer memory that Linux kernel must
> > + provide.
> > +
> > + If unsure, say N.
> > +
> > +config HAVE_HWSAMPLER
> > + bool
> > +
> > +config OPROFILE_HWSAMPLING_MODE
> > + bool
> > +
> > endmenu
> >
> > menu "Power Management"
> > Index: linux-2.6/arch/s390/oprofile/Makefile
> > ===================================================================
> > --- linux-2.6.orig/arch/s390/oprofile/Makefile
> > +++ linux-2.6/arch/s390/oprofile/Makefile
> > @@ -1,3 +1,4 @@
> > +obj-$(CONFIG_HWSAMPLER) += hwsampler.o
> > obj-$(CONFIG_OPROFILE) += oprofile.o
> >
> > DRIVER_OBJS = $(addprefix ../../../drivers/oprofile/, \
> > @@ -7,3 +8,8 @@ DRIVER_OBJS = $(addprefix ../../../drive
> > timer_int.o )
> >
> > oprofile-y := $(DRIVER_OBJS) init.o backtrace.o
> > +
> > +HW_SAMPLER_DRIVER_OBJS = $(addprefix ../../../drivers/s390/hwsampler/, \
> > + hwsampler-main.o smpctl.o )
> > +
> > +hwsampler-y := $(HW_SAMPLER_DRIVER_OBJS)
>
> Have you tried building this as a module. Not really sure, but I think it should be
>
see above
> hwsampler-$(CONFIG_HWSAMPLER) := ...
>
> See also my statement above about putting this to cpu init code
> instead of having a driver for it.
>
> -Robert
>
> >
> >
>
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