Re: [RFC PATCH 4/6] relay: add relay_reserve_cpu()
On Tue, 2007-07-03 at 23:17 -0400, Mathieu Desnoyers wrote: > * Tom Zanussi ([EMAIL PROTECTED]) wrote: > > This patch adds the ability to explicitly specify the per-cpu buffer > > to reserve space in. Needed for early DTI tracing. > > > > This should come with the ability to tell relay where the already > allocated static buffers are. Can you tell me a little more on why the > standard relay_reserve would not do the job? Is smp_processor_id() not > ready to output a sensible CPU id yet ? > In the case of early tracing, the DTI code uses a global buffer and saves the cpuid along with each event. Later, when the relay channel is available, the relogging code wants to put each event in the appropriate per-cpu relay buffer. The standard relay_reserve() always uses the current cpuid, rather than the cpuid attached to the event, which is not what we want. relay_reserve_cpu() simply allows a cpuid other than the current one to be used. Tom - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [RFC PATCH 4/6] relay: add relay_reserve_cpu()
On Tue, 2007-07-03 at 23:17 -0400, Mathieu Desnoyers wrote: * Tom Zanussi ([EMAIL PROTECTED]) wrote: This patch adds the ability to explicitly specify the per-cpu buffer to reserve space in. Needed for early DTI tracing. This should come with the ability to tell relay where the already allocated static buffers are. Can you tell me a little more on why the standard relay_reserve would not do the job? Is smp_processor_id() not ready to output a sensible CPU id yet ? In the case of early tracing, the DTI code uses a global buffer and saves the cpuid along with each event. Later, when the relay channel is available, the relogging code wants to put each event in the appropriate per-cpu relay buffer. The standard relay_reserve() always uses the current cpuid, rather than the cpuid attached to the event, which is not what we want. relay_reserve_cpu() simply allows a cpuid other than the current one to be used. Tom - To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [RFC PATCH 4/6] relay: add relay_reserve_cpu()
* Tom Zanussi ([EMAIL PROTECTED]) wrote:
> This patch adds the ability to explicitly specify the per-cpu buffer
> to reserve space in. Needed for early DTI tracing.
>
This should come with the ability to tell relay where the already
allocated static buffers are. Can you tell me a little more on why the
standard relay_reserve would not do the job? Is smp_processor_id() not
ready to output a sensible CPU id yet ?
> Signed-off-by: Tom Zanussi <[EMAIL PROTECTED]>
> Signed-off-by: David Wilder <[EMAIL PROTECTED]>
> ---
> relay.h | 33 +
> 1 file changed, 33 insertions(+)
>
> diff --git a/include/linux/relay.h b/include/linux/relay.h
> index 6caedef..37a7306 100644
> --- a/include/linux/relay.h
> +++ b/include/linux/relay.h
> @@ -269,6 +269,39 @@ static inline void *relay_reserve(struct rchan *chan,
> size_t length)
> }
>
> /**
> + * relay_reserve_cpu - reserve slot in given cpu's channel buffer
> + * @chan: relay channel
> + * @length: number of bytes to reserve
> + * @cpu: cpu to log to
> + *
> + * Returns pointer to reserved slot, NULL if full.
> + *
> + * Reserves a slot in the given cpu's channel buffer.
> + * Does not protect the buffer at all - caller must provide
> + * appropriate synchronization.
> + *
> + * NOTE: this is almost certainly not the function you want -
> + * use relay_reserve() instead for normal logging. This version
> + * is specialized for things like early tracing.
> + */
> +static inline void *relay_reserve_cpu(struct rchan *chan, size_t length,
> + unsigned int cpu)
> +{
> + void *reserved;
> + struct rchan_buf *buf = chan->buf[cpu];
> +
> + if (unlikely(buf->offset + length > buf->chan->subbuf_size)) {
> + length = relay_switch_subbuf(buf, length);
> + if (!length)
> + return NULL;
> + }
> + reserved = buf->data + buf->offset;
> + buf->offset += length;
> +
> + return reserved;
> +}
> +
> +/**
> * subbuf_start_reserve - reserve bytes at the start of a sub-buffer
> * @buf: relay channel buffer
> * @length: number of bytes to reserve
>
>
>
> -
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to [EMAIL PROTECTED]
> More majordomo info at http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at http://www.tux.org/lkml/
>
--
Mathieu Desnoyers
Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68
-
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Re: [RFC PATCH 4/6] relay: add relay_reserve_cpu()
* Tom Zanussi ([EMAIL PROTECTED]) wrote:
This patch adds the ability to explicitly specify the per-cpu buffer
to reserve space in. Needed for early DTI tracing.
This should come with the ability to tell relay where the already
allocated static buffers are. Can you tell me a little more on why the
standard relay_reserve would not do the job? Is smp_processor_id() not
ready to output a sensible CPU id yet ?
Signed-off-by: Tom Zanussi [EMAIL PROTECTED]
Signed-off-by: David Wilder [EMAIL PROTECTED]
---
relay.h | 33 +
1 file changed, 33 insertions(+)
diff --git a/include/linux/relay.h b/include/linux/relay.h
index 6caedef..37a7306 100644
--- a/include/linux/relay.h
+++ b/include/linux/relay.h
@@ -269,6 +269,39 @@ static inline void *relay_reserve(struct rchan *chan,
size_t length)
}
/**
+ * relay_reserve_cpu - reserve slot in given cpu's channel buffer
+ * @chan: relay channel
+ * @length: number of bytes to reserve
+ * @cpu: cpu to log to
+ *
+ * Returns pointer to reserved slot, NULL if full.
+ *
+ * Reserves a slot in the given cpu's channel buffer.
+ * Does not protect the buffer at all - caller must provide
+ * appropriate synchronization.
+ *
+ * NOTE: this is almost certainly not the function you want -
+ * use relay_reserve() instead for normal logging. This version
+ * is specialized for things like early tracing.
+ */
+static inline void *relay_reserve_cpu(struct rchan *chan, size_t length,
+ unsigned int cpu)
+{
+ void *reserved;
+ struct rchan_buf *buf = chan-buf[cpu];
+
+ if (unlikely(buf-offset + length buf-chan-subbuf_size)) {
+ length = relay_switch_subbuf(buf, length);
+ if (!length)
+ return NULL;
+ }
+ reserved = buf-data + buf-offset;
+ buf-offset += length;
+
+ return reserved;
+}
+
+/**
* subbuf_start_reserve - reserve bytes at the start of a sub-buffer
* @buf: relay channel buffer
* @length: number of bytes to reserve
-
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--
Mathieu Desnoyers
Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68
-
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Please read the FAQ at http://www.tux.org/lkml/
[RFC PATCH 4/6] relay: add relay_reserve_cpu()
This patch adds the ability to explicitly specify the per-cpu buffer
to reserve space in. Needed for early DTI tracing.
Signed-off-by: Tom Zanussi <[EMAIL PROTECTED]>
Signed-off-by: David Wilder <[EMAIL PROTECTED]>
---
relay.h | 33 +
1 file changed, 33 insertions(+)
diff --git a/include/linux/relay.h b/include/linux/relay.h
index 6caedef..37a7306 100644
--- a/include/linux/relay.h
+++ b/include/linux/relay.h
@@ -269,6 +269,39 @@ static inline void *relay_reserve(struct rchan *chan,
size_t length)
}
/**
+ * relay_reserve_cpu - reserve slot in given cpu's channel buffer
+ * @chan: relay channel
+ * @length: number of bytes to reserve
+ * @cpu: cpu to log to
+ *
+ * Returns pointer to reserved slot, NULL if full.
+ *
+ * Reserves a slot in the given cpu's channel buffer.
+ * Does not protect the buffer at all - caller must provide
+ * appropriate synchronization.
+ *
+ * NOTE: this is almost certainly not the function you want -
+ * use relay_reserve() instead for normal logging. This version
+ * is specialized for things like early tracing.
+ */
+static inline void *relay_reserve_cpu(struct rchan *chan, size_t length,
+ unsigned int cpu)
+{
+ void *reserved;
+ struct rchan_buf *buf = chan->buf[cpu];
+
+ if (unlikely(buf->offset + length > buf->chan->subbuf_size)) {
+ length = relay_switch_subbuf(buf, length);
+ if (!length)
+ return NULL;
+ }
+ reserved = buf->data + buf->offset;
+ buf->offset += length;
+
+ return reserved;
+}
+
+/**
* subbuf_start_reserve - reserve bytes at the start of a sub-buffer
* @buf: relay channel buffer
* @length: number of bytes to reserve
-
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Please read the FAQ at http://www.tux.org/lkml/
[RFC PATCH 4/6] relay: add relay_reserve_cpu()
This patch adds the ability to explicitly specify the per-cpu buffer
to reserve space in. Needed for early DTI tracing.
Signed-off-by: Tom Zanussi [EMAIL PROTECTED]
Signed-off-by: David Wilder [EMAIL PROTECTED]
---
relay.h | 33 +
1 file changed, 33 insertions(+)
diff --git a/include/linux/relay.h b/include/linux/relay.h
index 6caedef..37a7306 100644
--- a/include/linux/relay.h
+++ b/include/linux/relay.h
@@ -269,6 +269,39 @@ static inline void *relay_reserve(struct rchan *chan,
size_t length)
}
/**
+ * relay_reserve_cpu - reserve slot in given cpu's channel buffer
+ * @chan: relay channel
+ * @length: number of bytes to reserve
+ * @cpu: cpu to log to
+ *
+ * Returns pointer to reserved slot, NULL if full.
+ *
+ * Reserves a slot in the given cpu's channel buffer.
+ * Does not protect the buffer at all - caller must provide
+ * appropriate synchronization.
+ *
+ * NOTE: this is almost certainly not the function you want -
+ * use relay_reserve() instead for normal logging. This version
+ * is specialized for things like early tracing.
+ */
+static inline void *relay_reserve_cpu(struct rchan *chan, size_t length,
+ unsigned int cpu)
+{
+ void *reserved;
+ struct rchan_buf *buf = chan-buf[cpu];
+
+ if (unlikely(buf-offset + length buf-chan-subbuf_size)) {
+ length = relay_switch_subbuf(buf, length);
+ if (!length)
+ return NULL;
+ }
+ reserved = buf-data + buf-offset;
+ buf-offset += length;
+
+ return reserved;
+}
+
+/**
* subbuf_start_reserve - reserve bytes at the start of a sub-buffer
* @buf: relay channel buffer
* @length: number of bytes to reserve
-
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