Re: [dpdk-dev] [PATCH v9 2/2] timer: support EAL functions on Windows

[Fady Bader <fady@mellanox.com>]

> -----Original Message-----
> From: Ranjit Menon <ranjit.menon@intel.com>
> Sent: Thursday, June 18, 2020 1:16 AM
> To: Fady Bader <fady@mellanox.com>; dev@dpdk.org
> Cc: Thomas Monjalon <thomas@monjalon.net>; Tasnim Bashar
> <tbashar@mellanox.com>; Tal Shnaiderman <talshn@mellanox.com>; Yohad Tor
> <yohadt@mellanox.com>; dmitry.kozliuk@gmail.com;
> harini.ramakrishnan@microsoft.com; ocardona@microsoft.com;
> pallavi.kadam@intel.com
> Subject: Re: [PATCH v9 2/2] timer: support EAL functions on Windows
> 
> 
> On 6/17/2020 2:39 AM, Fady Bader wrote:
> > Implemented the needed Windows eal timer functions.
> >
> > Signed-off-by: Fady Bader <fady@mellanox.com>
> > ---
> >   lib/librte_eal/common/meson.build       |  1 +
> >   lib/librte_eal/windows/eal.c            |  6 +++
> >   lib/librte_eal/windows/eal_timer.c      | 91
> +++++++++++++++++++++++++++++++++
> >   lib/librte_eal/windows/include/rte_os.h |  2 +
> >   lib/librte_eal/windows/meson.build      |  1 +
> >   5 files changed, 101 insertions(+)
> >   create mode 100644 lib/librte_eal/windows/eal_timer.c
> >
> > diff --git a/lib/librte_eal/common/meson.build
> > b/lib/librte_eal/common/meson.build
> > index 3108442697..4bdf77922f 100644
> > --- a/lib/librte_eal/common/meson.build
> > +++ b/lib/librte_eal/common/meson.build
> > @@ -26,6 +26,7 @@ if is_windows
> >   		'malloc_elem.c',
> >   		'malloc_heap.c',
> >   		'rte_malloc.c',
> > +		'eal_common_timer.c',
> >   	)
> >   	subdir_done()
> >   endif
> > diff --git a/lib/librte_eal/windows/eal.c
> > b/lib/librte_eal/windows/eal.c index 427a5557fa..b6bffd3d92 100644
> > --- a/lib/librte_eal/windows/eal.c
> > +++ b/lib/librte_eal/windows/eal.c
> > @@ -354,6 +354,12 @@ rte_eal_init(int argc, char **argv)
> >   		return -1;
> >   	}
> >
> > +	if (rte_eal_timer_init() < 0) {
> > +		rte_eal_init_alert("Cannot init TSC timer");
> > +		rte_errno = EFAULT;
> > +		return -1;
> > +	}
> > +
> >   	eal_thread_init_master(rte_config.master_lcore);
> >
> >   	RTE_LCORE_FOREACH_SLAVE(i) {
> > diff --git a/lib/librte_eal/windows/eal_timer.c
> > b/lib/librte_eal/windows/eal_timer.c
> > new file mode 100644
> > index 0000000000..59099e8942
> > --- /dev/null
> > +++ b/lib/librte_eal/windows/eal_timer.c
> > @@ -0,0 +1,91 @@
> > +/* SPDX-License-Identifier: BSD-3-Clause
> > + * Copyright 2020 Mellanox Technologies, Ltd  */ #include
> > +<inttypes.h>
> > +
> > +#include <rte_windows.h>
> > +#include <rte_common.h>
> > +#include <rte_cycles.h>
> > +#include <rte_eal.h>
> > +#include <rte_errno.h>
> > +#include "eal_private.h"
> > +
> > +#define US_PER_SEC 1E6
> > +#define CYC_PER_10MHZ 1E7
> > +
> > +void
> > +rte_delay_us_sleep(unsigned int us)
> > +{
> > +	HANDLE timer;
> > +	LARGE_INTEGER due_time;
> > +
> > +	/* create waitable timer */
> > +	timer = CreateWaitableTimer(NULL, TRUE, NULL);
> > +	if (!timer) {
> > +		RTE_LOG_WIN32_ERR("CreateWaitableTimer()");
> > +		rte_errno = ENOMEM;
> > +		return;
> > +	}
> > +
> > +	/*
> > +	 * due_time's uom is 100 ns, multiply by 10 to convert to microseconds
> > +	 * set us microseconds time for timer
> > +	 */
> > +	due_time.QuadPart = -((int64_t)us * 10);
> > +	if (!SetWaitableTimer(timer, &due_time, 0, NULL, NULL, FALSE)) {
> > +		RTE_LOG_WIN32_ERR("SetWaitableTimer()");
> > +		rte_errno = EINVAL;
> > +		goto end;
> > +	}
> > +	/* start wait for timer for us microseconds */
> > +	if (WaitForSingleObject(timer, INFINITE) == WAIT_FAILED) {
> > +		RTE_LOG_WIN32_ERR("WaitForSingleObject()");
> > +		rte_errno = EINVAL;
> > +	}
> > +
> > +end:
> > +	CloseHandle(timer);
> > +}
> > +
> > +uint64_t
> > +get_tsc_freq(void)
> > +{
> > +	LARGE_INTEGER t_start, t_end, elapsed_us;
> > +	LARGE_INTEGER frequency;
> > +	uint64_t tsc_hz;
> > +	uint64_t end, start = rte_get_tsc_cycles();
> 
> I think a better implementation may be:
> 
> uint64_t start, end;
> 
> QueryPerformanceFrequency(&frequency);
> 
> start = rte_get_tsc_cycles();
> QueryPerformanceCounter(&t_start);
> 
> rte_delay_us_sleep(US_PER_SEC / 10); /* 1/10 second */
> 
> .....
> 

You are correct.
I've sent another patch.

Thanks,
Fady

> > +
> > +	QueryPerformanceCounter(&t_start);
> > +	QueryPerformanceFrequency(&frequency);
> > +
> > +	rte_delay_us_sleep(US_PER_SEC / 10); /* 1/10 second */
> > +
> > +	if (rte_errno != 0)
> > +		return 0;
> > +
> > +	QueryPerformanceCounter(&t_end);
> > +	end = rte_get_tsc_cycles();
> > +
> > +	elapsed_us.QuadPart = t_end.QuadPart - t_start.QuadPart;
> > +
> > +	/*
> > +	 * To guard against loss-of-precision, convert to microseconds
> > +	 * *before* dividing by ticks-per-second.
> > +	 */
> > +	elapsed_us.QuadPart *= US_PER_SEC;
> > +	elapsed_us.QuadPart /= frequency.QuadPart;
> > +
> > +	double secs = ((double)elapsed_us.QuadPart)/US_PER_SEC;
> > +	tsc_hz = (uint64_t)((end - start)/secs);
> > +
> > +	/* Round up to 10Mhz. 1E7 ~ 10Mhz */
> > +	return RTE_ALIGN_MUL_NEAR(tsc_hz, CYC_PER_10MHZ); }
> 
> [Snip]
> 
> ranjit m.