On 03/09/15 16:30, Mike Holmes wrote:
Call concluded that we generate a platfomr/linux-generic/arch for this
case because it is important to retain the low jitter / overhead
characteristics for the test case duration metrics that use this API.
In general we will avoid arch specifics in linux-generic.
OK.
This way we remove the #ifdefs in one file with configuration time
switches to either use sys calls or an arch dependent lowest overhead
implementation which is contained in its own arch/xxxx c file similar
to Linux.
On 9 March 2015 at 09:03, Bill Fischofer <[email protected]
<mailto:[email protected]>> wrote:
I'm not sure what the benefit would be for this. ODP and Linux
take a different approach to optimization. Linux tries to be a
single implementation optimized for multiple platforms, hence the
use of arch directories. ODP, however is a single
/specification/ optimized across multiple implementations.
odp-dpdk is intended to be the optimized implementation for x86,
just as the implementations provided by Cavium, TI, etc. are
designed to be the optimized implementations for their respective
platforms. As such, linux-generic has no need for
platform-specific optimizations, however organized.
On Mon, Mar 9, 2015 at 7:50 AM, Mike Holmes
<[email protected] <mailto:[email protected]>> wrote:
On 9 March 2015 at 08:45, Savolainen, Petri (Nokia - FI/Espoo)
<[email protected]
<mailto:[email protected]>> wrote:
Performance is not the main concern here, but cycle count
measurement accuracy. E.g. Intel rdtsc cycle counter read
latency is few cycles where as clock_gettime() seems to
take over a thousand. System call latencies also vary
since those may launch other kernel services, which adds
jitter to cycle count measurements.
Could we organize arch specific stuff better (no #ifdefs,
but configure/build mechanism) and continue to support
e.g. rdtsc.
We had originally proposed an arch directory to capture
architecture differences that should be common to all X86, ARM
etc regardless of the platform and its specific accelerators.
If this were at the top in odp/arch then I would imaging they
would be reusable implementations of API functions.
I think this should be a topic for the ARCH call in 10 mins.
-Petri
*From:*[email protected]
<mailto:[email protected]>
[mailto:[email protected]
<mailto:[email protected]>] *On Behalf Of
*ext Bill Fischofer
*Sent:* Friday, March 06, 2015 6:42 PM
*To:* Mike Holmes
*Cc:* lng-odp
*Subject:* Re: [lng-odp] [PATCH] linux-generic: time:
remove platform specific acceleration
I agree with Mike. Now that we have an official LNG
performance implementation, linux-generic should focus on
being a simple and clean functional implementation that
elaborates the intended behavior of the ODP APIs without
being overly concerned with performance. That doesn't
mean we don't do straightforward functional optimizations
that are algorithmic in nature, just that there shouldn't
be any platform-specific tuning paths in linux-generic.
On Fri, Mar 6, 2015 at 10:35 AM, Mike Holmes
<[email protected] <mailto:[email protected]>>
wrote:
The DPDK implementation will take the X86 optimizations,
presumably Cavium already have Octeon acceleration in
their own ODP implementation.
The linux generic implementation should be a model for the
behavior of ODP, it happens to run in Linux but that
should not be confused with it being used in any real
application.
If we fill it with optimizations it will be harder to
maintain as a pure model.
Mike
On 6 March 2015 at 11:26, Maxim Uvarov
<[email protected] <mailto:[email protected]>>
wrote:
Where should be that implementations placed if we want
other platform to reuse them?
Maxim.
On 03/06/15 19:22, Mike Holmes wrote:
Linux-generic should be a reference implementation and
does not need
archetecture specific acceleration.
Signed-off-by: Mike Holmes <[email protected]
<mailto:[email protected]>>
---
platform/linux-generic/odp_time.c | 47
+++------------------------------------
1 file changed, 3 insertions(+), 44 deletions(-)
diff --git a/platform/linux-generic/odp_time.c
b/platform/linux-generic/odp_time.c
index 31d6656..6f40361 100644
--- a/platform/linux-generic/odp_time.c
+++ b/platform/linux-generic/odp_time.c
@@ -6,52 +6,13 @@
#define _POSIX_C_SOURCE 200809L
+#include <time.h>
#include <odp/time.h>
-#include <odp/hints.h>
#include <odp/system_info.h>
-
-#define GIGA 1000000000
-
-#if defined __x86_64__ || defined __i386__
-
-uint64_t odp_time_cycles(void)
-{
- union {
- uint64_t tsc_64;
- struct {
- uint32_t lo_32;
- uint32_t hi_32;
- };
- } tsc;
-
- __asm__ __volatile__ ("rdtsc" :
- "=a" (tsc.lo_32),
- "=d" (tsc.hi_32) : : "memory");
-
- return tsc.tsc_64;
-}
-
-
-#elif defined __OCTEON__
-
-uint64_t odp_time_cycles(void)
-{
- #define CVMX_TMP_STR(x) CVMX_TMP_STR2(x)
- #define CVMX_TMP_STR2(x) #x
- uint64_t cycle;
-
- __asm__ __volatile__ ("rdhwr %[rt],$" CVMX_TMP_STR(31) :
- [rt] "=d" (cycle) : : "memory");
-
- return cycle;
-}
-
-#else
-
-#include <time.h>
-#include <stdlib.h>
#include <odp_debug_internal.h>
+#define GIGA 1000000000
+
uint64_t odp_time_cycles(void)
{
struct timespec time;
@@ -74,8 +35,6 @@ uint64_t odp_time_cycles(void)
return cycles;
}
-#endif
-
uint64_t odp_time_diff_cycles(uint64_t t1, uint64_t t2)
{
if (odp_likely(t2 > t1))
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Mike Holmes
Technical Manager - Linaro Networking Group
Linaro.org <http://www.linaro.org/>***│ *Open source
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Mike Holmes
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Linaro.org <http://www.linaro.org/>***│ *Open source software
for ARM SoCs
--
Mike Holmes
Technical Manager - Linaro Networking Group
Linaro.org <http://www.linaro.org/>***│ *Open source software for ARM SoCs
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