[v1,1/2] eal/x86: add WC store function
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Commit Message
Add rte_write32_wc function that implements a WC store
using movdiri instruction.
Signed-off-by: Radu Nicolau <radu.nicolau@intel.com>
---
lib/librte_eal/x86/include/rte_io.h | 20 ++++++++++++++++++++
1 file changed, 20 insertions(+)
Comments
On Thu, Jun 11, 2020 at 3:41 PM Radu Nicolau <radu.nicolau@intel.com> wrote:
>
> Add rte_write32_wc function that implements a WC store
> using movdiri instruction.
>
> Signed-off-by: Radu Nicolau <radu.nicolau@intel.com>
> ---
> lib/librte_eal/x86/include/rte_io.h | 20 ++++++++++++++++++++
> 1 file changed, 20 insertions(+)
>
> diff --git a/lib/librte_eal/x86/include/rte_io.h b/lib/librte_eal/x86/include/rte_io.h
> index 2db71b1..3d74bec 100644
> --- a/lib/librte_eal/x86/include/rte_io.h
> +++ b/lib/librte_eal/x86/include/rte_io.h
> @@ -11,6 +11,26 @@ extern "C" {
>
> #include "generic/rte_io.h"
>
> +/**
> + * Write a 32-bit value to I/O device memory address *addr*.
> + * Uses MOVDIRI instruction to perform a direct-store operation using WC
> + * memory write protocol.
It will be an x86 specific API, Please change the API name to reflect that.
> + *
> + * @param value
> + * Value to write
> + * @param addr
> + * I/O memory address to write the value to
> + */
> +static __rte_always_inline void
> +rte_write32_wc(uint32_t value, volatile void *addr)
> +{
> + asm volatile("sfence\n\t"
> + /* MOVDIRI */
> + ".byte 0x40, 0x0f, 0x38, 0xf9, 0x02"
> + :
> + : "a" (value), "d" (addr));
> +}
> +
> #ifdef __cplusplus
> }
> #endif
> --
> 2.7.4
>
On 6/11/2020 1:23 PM, Jerin Jacob wrote:
> On Thu, Jun 11, 2020 at 3:41 PM Radu Nicolau <radu.nicolau@intel.com> wrote:
>> Add rte_write32_wc function that implements a WC store
>> using movdiri instruction.
>>
>> Signed-off-by: Radu Nicolau <radu.nicolau@intel.com>
>> ---
>> lib/librte_eal/x86/include/rte_io.h | 20 ++++++++++++++++++++
>> 1 file changed, 20 insertions(+)
>>
>> diff --git a/lib/librte_eal/x86/include/rte_io.h b/lib/librte_eal/x86/include/rte_io.h
>> index 2db71b1..3d74bec 100644
>> --- a/lib/librte_eal/x86/include/rte_io.h
>> +++ b/lib/librte_eal/x86/include/rte_io.h
>> @@ -11,6 +11,26 @@ extern "C" {
>>
>> #include "generic/rte_io.h"
>>
>> +/**
>> + * Write a 32-bit value to I/O device memory address *addr*.
>> + * Uses MOVDIRI instruction to perform a direct-store operation using WC
>> + * memory write protocol.
> It will be an x86 specific API, Please change the API name to reflect that.
>
You mean something like rte_x86_write32_wc?
On Thu, Jun 11, 2020 at 7:26 PM Nicolau, Radu <radu.nicolau@intel.com> wrote:
>
>
> On 6/11/2020 1:23 PM, Jerin Jacob wrote:
> > On Thu, Jun 11, 2020 at 3:41 PM Radu Nicolau <radu.nicolau@intel.com> wrote:
> >> Add rte_write32_wc function that implements a WC store
> >> using movdiri instruction.
> >>
> >> Signed-off-by: Radu Nicolau <radu.nicolau@intel.com>
> >> ---
> >> lib/librte_eal/x86/include/rte_io.h | 20 ++++++++++++++++++++
> >> 1 file changed, 20 insertions(+)
> >>
> >> diff --git a/lib/librte_eal/x86/include/rte_io.h b/lib/librte_eal/x86/include/rte_io.h
> >> index 2db71b1..3d74bec 100644
> >> --- a/lib/librte_eal/x86/include/rte_io.h
> >> +++ b/lib/librte_eal/x86/include/rte_io.h
> >> @@ -11,6 +11,26 @@ extern "C" {
> >>
> >> #include "generic/rte_io.h"
> >>
> >> +/**
> >> + * Write a 32-bit value to I/O device memory address *addr*.
> >> + * Uses MOVDIRI instruction to perform a direct-store operation using WC
> >> + * memory write protocol.
> > It will be an x86 specific API, Please change the API name to reflect that.
> >
> You mean something like rte_x86_write32_wc?
Yes. Something like that...
Hi Radu,
>
> Add rte_write32_wc function that implements a WC store
> using movdiri instruction.
Probably worth to add 1-2 lines of text
explaining what are the advantages (perf improvement or whatever).
>
> Signed-off-by: Radu Nicolau <radu.nicolau@intel.com>
> ---
> lib/librte_eal/x86/include/rte_io.h | 20 ++++++++++++++++++++
> 1 file changed, 20 insertions(+)
>
> diff --git a/lib/librte_eal/x86/include/rte_io.h b/lib/librte_eal/x86/include/rte_io.h
> index 2db71b1..3d74bec 100644
> --- a/lib/librte_eal/x86/include/rte_io.h
> +++ b/lib/librte_eal/x86/include/rte_io.h
> @@ -11,6 +11,26 @@ extern "C" {
>
> #include "generic/rte_io.h"
>
> +/**
> + * Write a 32-bit value to I/O device memory address *addr*.
> + * Uses MOVDIRI instruction to perform a direct-store operation using WC
> + * memory write protocol.
> + *
> + * @param value
> + * Value to write
> + * @param addr
> + * I/O memory address to write the value to
> + */
> +static __rte_always_inline void
> +rte_write32_wc(uint32_t value, volatile void *addr)
> +{
> + asm volatile("sfence\n\t"
Why not rte_wmb()?
> + /* MOVDIRI */
> + ".byte 0x40, 0x0f, 0x38, 0xf9, 0x02"
> + :
> + : "a" (value), "d" (addr));
> +}
> +
> #ifdef __cplusplus
> }
> #endif
> --
> 2.7.4
@@ -11,6 +11,26 @@ extern "C" {
#include "generic/rte_io.h"
+/**
+ * Write a 32-bit value to I/O device memory address *addr*.
+ * Uses MOVDIRI instruction to perform a direct-store operation using WC
+ * memory write protocol.
+ *
+ * @param value
+ * Value to write
+ * @param addr
+ * I/O memory address to write the value to
+ */
+static __rte_always_inline void
+rte_write32_wc(uint32_t value, volatile void *addr)
+{
+ asm volatile("sfence\n\t"
+ /* MOVDIRI */
+ ".byte 0x40, 0x0f, 0x38, 0xf9, 0x02"
+ :
+ : "a" (value), "d" (addr));
+}
+
#ifdef __cplusplus
}
#endif