* [PATCH infiniband-diags] query_smp.c: Avoid busy looping in process_one_recv
@ 2015-04-16 14:26 Hal Rosenstock
[not found] ` <552FC690.1010807-LDSdmyG8hGV8YrgS2mwiifqBs+8SCbDb@public.gmane.org>
0 siblings, 1 reply; 3+ messages in thread
From: Hal Rosenstock @ 2015-04-16 14:26 UTC (permalink / raw)
To: Ira Weiny
Cc: Vladimir Koushnir,
linux-rdma (linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org)
From: Vladimir Koushnir <vladimirk-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
Date: Thu, 16 Apr 2015 14:11:16 +0300
Today, process_one_recv calls umad_recv with zero timeout.
That means umad_recv will use non-blocking read() without polling,
In many cases, this causes busy loop.
In the fix, umad_recv is invoked with -1 (infinite timeout) and the read()
will occur only when poll exits. Also, no longer need to check for
EWOULDBLOCK.
Signed-off-by: Vladimir Koushnir <vladimirk-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
Signed-off-by: Hal Rosenstock <hal-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
---
libibnetdisc/src/query_smp.c | 2 +-
1 files changed, 1 insertions(+), 3 deletions(-)
diff --git a/libibnetdisc/src/query_smp.c b/libibnetdisc/src/query_smp.c
index 28620b4..8f179e4 100644
--- a/libibnetdisc/src/query_smp.c
+++ b/libibnetdisc/src/query_smp.c
@@ -171,9 +171,7 @@ static int process_one_recv(smp_engine_t * engine)
/* wait for the next message */
if ((rc = umad_recv(engine->umad_fd, umad, &length,
- 0)) < 0) {
- if (rc == -EWOULDBLOCK)
- return 0;
+ -1)) < 0) {
IBND_ERROR("umad_recv failed: %d\n", rc);
return -1;
}
--
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^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH infiniband-diags] query_smp.c: Avoid busy looping in process_one_recv
[not found] ` <552FC690.1010807-LDSdmyG8hGV8YrgS2mwiifqBs+8SCbDb@public.gmane.org>
@ 2015-04-22 14:44 ` ira.weiny
2015-07-03 15:21 ` ira.weiny
1 sibling, 0 replies; 3+ messages in thread
From: ira.weiny @ 2015-04-22 14:44 UTC (permalink / raw)
To: Hal Rosenstock
Cc: Vladimir Koushnir,
linux-rdma (linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org)
On Thu, Apr 16, 2015 at 10:26:24AM -0400, Hal Rosenstock wrote:
> From: Vladimir Koushnir <vladimirk-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
> Date: Thu, 16 Apr 2015 14:11:16 +0300
>
> Today, process_one_recv calls umad_recv with zero timeout.
> That means umad_recv will use non-blocking read() without polling,
> In many cases, this causes busy loop.
>
> In the fix, umad_recv is invoked with -1 (infinite timeout) and the read()
> will occur only when poll exits. Also, no longer need to check for
> EWOULDBLOCK.
Has this been tested on broken fabrics where SMAs don't respond?
I know that we should recv something (ie timed out Send) for every MAD
submitted to the kernel but I seem to remember a reason we did not use a
timeout. But that may have been for a previous implementation which no longer
exists. I can't remember.
Ira
>
> Signed-off-by: Vladimir Koushnir <vladimirk-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
> Signed-off-by: Hal Rosenstock <hal-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
> ---
> libibnetdisc/src/query_smp.c | 2 +-
> 1 files changed, 1 insertions(+), 3 deletions(-)
>
> diff --git a/libibnetdisc/src/query_smp.c b/libibnetdisc/src/query_smp.c
> index 28620b4..8f179e4 100644
> --- a/libibnetdisc/src/query_smp.c
> +++ b/libibnetdisc/src/query_smp.c
> @@ -171,9 +171,7 @@ static int process_one_recv(smp_engine_t * engine)
>
> /* wait for the next message */
> if ((rc = umad_recv(engine->umad_fd, umad, &length,
> - 0)) < 0) {
> - if (rc == -EWOULDBLOCK)
> - return 0;
> + -1)) < 0) {
> IBND_ERROR("umad_recv failed: %d\n", rc);
> return -1;
> }
--
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^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH infiniband-diags] query_smp.c: Avoid busy looping in process_one_recv
[not found] ` <552FC690.1010807-LDSdmyG8hGV8YrgS2mwiifqBs+8SCbDb@public.gmane.org>
2015-04-22 14:44 ` ira.weiny
@ 2015-07-03 15:21 ` ira.weiny
1 sibling, 0 replies; 3+ messages in thread
From: ira.weiny @ 2015-07-03 15:21 UTC (permalink / raw)
To: Hal Rosenstock
Cc: Vladimir Koushnir,
linux-rdma (linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org)
On Thu, Apr 16, 2015 at 10:26:24AM -0400, Hal Rosenstock wrote:
> From: Vladimir Koushnir <vladimirk-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
> Date: Thu, 16 Apr 2015 14:11:16 +0300
>
> Today, process_one_recv calls umad_recv with zero timeout.
> That means umad_recv will use non-blocking read() without polling,
> In many cases, this causes busy loop.
>
> In the fix, umad_recv is invoked with -1 (infinite timeout) and the read()
> will occur only when poll exits. Also, no longer need to check for
> EWOULDBLOCK.
>
> Signed-off-by: Vladimir Koushnir <vladimirk-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
> Signed-off-by: Hal Rosenstock <hal-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
Thanks applied,
Ira
> ---
> libibnetdisc/src/query_smp.c | 2 +-
> 1 files changed, 1 insertions(+), 3 deletions(-)
>
> diff --git a/libibnetdisc/src/query_smp.c b/libibnetdisc/src/query_smp.c
> index 28620b4..8f179e4 100644
> --- a/libibnetdisc/src/query_smp.c
> +++ b/libibnetdisc/src/query_smp.c
> @@ -171,9 +171,7 @@ static int process_one_recv(smp_engine_t * engine)
>
> /* wait for the next message */
> if ((rc = umad_recv(engine->umad_fd, umad, &length,
> - 0)) < 0) {
> - if (rc == -EWOULDBLOCK)
> - return 0;
> + -1)) < 0) {
> IBND_ERROR("umad_recv failed: %d\n", rc);
> return -1;
> }
--
To unsubscribe from this list: send the line "unsubscribe linux-rdma" in
the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2015-07-03 15:21 UTC | newest]
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2015-04-16 14:26 [PATCH infiniband-diags] query_smp.c: Avoid busy looping in process_one_recv Hal Rosenstock
[not found] ` <552FC690.1010807-LDSdmyG8hGV8YrgS2mwiifqBs+8SCbDb@public.gmane.org>
2015-04-22 14:44 ` ira.weiny
2015-07-03 15:21 ` ira.weiny
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