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[PATCH v3 3/3] Fix sizing of tape read buffers.
22+ messages / 2 participants
[nested] [flat]

* [PATCH v3 3/3] Fix sizing of tape read buffers.
@ 2021-01-22 20:59 Heikki Linnakangas <[email protected]>
  0 siblings, 0 replies; 22+ messages in thread

From: Heikki Linnakangas @ 2021-01-22 20:59 UTC (permalink / raw)

---
 src/backend/utils/sort/tuplesort.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/backend/utils/sort/tuplesort.c b/src/backend/utils/sort/tuplesort.c
index 14104643e78..aff2f201f52 100644
--- a/src/backend/utils/sort/tuplesort.c
+++ b/src/backend/utils/sort/tuplesort.c
@@ -2658,7 +2658,7 @@ merge_read_buffer_size(int64 avail_mem, int nInputTapes, int nInputRuns,
 	 * we derive the input buffer size from the amount of memory available,
 	 * and M and N.
 	 */
-	return (avail_mem - TAPE_BUFFER_OVERHEAD * nOutputTapes) / nInputTapes;
+	return Max((avail_mem - TAPE_BUFFER_OVERHEAD * nOutputTapes) / nInputTapes, 0);
 }
 
 /*
-- 
2.29.2


--------------631E0A48DCAEA386819DFCEC--





^ permalink  raw  reply  [nested|flat] 22+ messages in thread

* [PATCH v3 3/3] Fix sizing of tape read buffers.
@ 2021-01-22 20:59 Heikki Linnakangas <[email protected]>
  0 siblings, 0 replies; 22+ messages in thread

From: Heikki Linnakangas @ 2021-01-22 20:59 UTC (permalink / raw)

---
 src/backend/utils/sort/tuplesort.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/backend/utils/sort/tuplesort.c b/src/backend/utils/sort/tuplesort.c
index 14104643e78..aff2f201f52 100644
--- a/src/backend/utils/sort/tuplesort.c
+++ b/src/backend/utils/sort/tuplesort.c
@@ -2658,7 +2658,7 @@ merge_read_buffer_size(int64 avail_mem, int nInputTapes, int nInputRuns,
 	 * we derive the input buffer size from the amount of memory available,
 	 * and M and N.
 	 */
-	return (avail_mem - TAPE_BUFFER_OVERHEAD * nOutputTapes) / nInputTapes;
+	return Max((avail_mem - TAPE_BUFFER_OVERHEAD * nOutputTapes) / nInputTapes, 0);
 }
 
 /*
-- 
2.29.2


--------------631E0A48DCAEA386819DFCEC--





^ permalink  raw  reply  [nested|flat] 22+ messages in thread

* [PATCH v3 3/3] Fix sizing of tape read buffers.
@ 2021-01-22 20:59 Heikki Linnakangas <[email protected]>
  0 siblings, 0 replies; 22+ messages in thread

From: Heikki Linnakangas @ 2021-01-22 20:59 UTC (permalink / raw)

---
 src/backend/utils/sort/tuplesort.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/backend/utils/sort/tuplesort.c b/src/backend/utils/sort/tuplesort.c
index 14104643e78..aff2f201f52 100644
--- a/src/backend/utils/sort/tuplesort.c
+++ b/src/backend/utils/sort/tuplesort.c
@@ -2658,7 +2658,7 @@ merge_read_buffer_size(int64 avail_mem, int nInputTapes, int nInputRuns,
 	 * we derive the input buffer size from the amount of memory available,
 	 * and M and N.
 	 */
-	return (avail_mem - TAPE_BUFFER_OVERHEAD * nOutputTapes) / nInputTapes;
+	return Max((avail_mem - TAPE_BUFFER_OVERHEAD * nOutputTapes) / nInputTapes, 0);
 }
 
 /*
-- 
2.29.2


--------------631E0A48DCAEA386819DFCEC--





^ permalink  raw  reply  [nested|flat] 22+ messages in thread

* [PATCH v3 3/3] Fix sizing of tape read buffers.
@ 2021-01-22 20:59 Heikki Linnakangas <[email protected]>
  0 siblings, 0 replies; 22+ messages in thread

From: Heikki Linnakangas @ 2021-01-22 20:59 UTC (permalink / raw)

---
 src/backend/utils/sort/tuplesort.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/backend/utils/sort/tuplesort.c b/src/backend/utils/sort/tuplesort.c
index 14104643e78..aff2f201f52 100644
--- a/src/backend/utils/sort/tuplesort.c
+++ b/src/backend/utils/sort/tuplesort.c
@@ -2658,7 +2658,7 @@ merge_read_buffer_size(int64 avail_mem, int nInputTapes, int nInputRuns,
 	 * we derive the input buffer size from the amount of memory available,
 	 * and M and N.
 	 */
-	return (avail_mem - TAPE_BUFFER_OVERHEAD * nOutputTapes) / nInputTapes;
+	return Max((avail_mem - TAPE_BUFFER_OVERHEAD * nOutputTapes) / nInputTapes, 0);
 }
 
 /*
-- 
2.29.2


--------------631E0A48DCAEA386819DFCEC--





^ permalink  raw  reply  [nested|flat] 22+ messages in thread

* [PATCH v3 3/3] Fix sizing of tape read buffers.
@ 2021-01-22 20:59 Heikki Linnakangas <[email protected]>
  0 siblings, 0 replies; 22+ messages in thread

From: Heikki Linnakangas @ 2021-01-22 20:59 UTC (permalink / raw)

---
 src/backend/utils/sort/tuplesort.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/backend/utils/sort/tuplesort.c b/src/backend/utils/sort/tuplesort.c
index 14104643e78..aff2f201f52 100644
--- a/src/backend/utils/sort/tuplesort.c
+++ b/src/backend/utils/sort/tuplesort.c
@@ -2658,7 +2658,7 @@ merge_read_buffer_size(int64 avail_mem, int nInputTapes, int nInputRuns,
 	 * we derive the input buffer size from the amount of memory available,
 	 * and M and N.
 	 */
-	return (avail_mem - TAPE_BUFFER_OVERHEAD * nOutputTapes) / nInputTapes;
+	return Max((avail_mem - TAPE_BUFFER_OVERHEAD * nOutputTapes) / nInputTapes, 0);
 }
 
 /*
-- 
2.29.2


--------------631E0A48DCAEA386819DFCEC--





^ permalink  raw  reply  [nested|flat] 22+ messages in thread

* [PATCH v3 3/3] Fix sizing of tape read buffers.
@ 2021-01-22 20:59 Heikki Linnakangas <[email protected]>
  0 siblings, 0 replies; 22+ messages in thread

From: Heikki Linnakangas @ 2021-01-22 20:59 UTC (permalink / raw)

---
 src/backend/utils/sort/tuplesort.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/backend/utils/sort/tuplesort.c b/src/backend/utils/sort/tuplesort.c
index 14104643e78..aff2f201f52 100644
--- a/src/backend/utils/sort/tuplesort.c
+++ b/src/backend/utils/sort/tuplesort.c
@@ -2658,7 +2658,7 @@ merge_read_buffer_size(int64 avail_mem, int nInputTapes, int nInputRuns,
 	 * we derive the input buffer size from the amount of memory available,
 	 * and M and N.
 	 */
-	return (avail_mem - TAPE_BUFFER_OVERHEAD * nOutputTapes) / nInputTapes;
+	return Max((avail_mem - TAPE_BUFFER_OVERHEAD * nOutputTapes) / nInputTapes, 0);
 }
 
 /*
-- 
2.29.2


--------------631E0A48DCAEA386819DFCEC--





^ permalink  raw  reply  [nested|flat] 22+ messages in thread

* [PATCH v3 3/3] Fix sizing of tape read buffers.
@ 2021-01-22 20:59 Heikki Linnakangas <[email protected]>
  0 siblings, 0 replies; 22+ messages in thread

From: Heikki Linnakangas @ 2021-01-22 20:59 UTC (permalink / raw)

---
 src/backend/utils/sort/tuplesort.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/backend/utils/sort/tuplesort.c b/src/backend/utils/sort/tuplesort.c
index 14104643e78..aff2f201f52 100644
--- a/src/backend/utils/sort/tuplesort.c
+++ b/src/backend/utils/sort/tuplesort.c
@@ -2658,7 +2658,7 @@ merge_read_buffer_size(int64 avail_mem, int nInputTapes, int nInputRuns,
 	 * we derive the input buffer size from the amount of memory available,
 	 * and M and N.
 	 */
-	return (avail_mem - TAPE_BUFFER_OVERHEAD * nOutputTapes) / nInputTapes;
+	return Max((avail_mem - TAPE_BUFFER_OVERHEAD * nOutputTapes) / nInputTapes, 0);
 }
 
 /*
-- 
2.29.2


--------------631E0A48DCAEA386819DFCEC--





^ permalink  raw  reply  [nested|flat] 22+ messages in thread

* [PATCH v3 3/3] Fix sizing of tape read buffers.
@ 2021-01-22 20:59 Heikki Linnakangas <[email protected]>
  0 siblings, 0 replies; 22+ messages in thread

From: Heikki Linnakangas @ 2021-01-22 20:59 UTC (permalink / raw)

---
 src/backend/utils/sort/tuplesort.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/backend/utils/sort/tuplesort.c b/src/backend/utils/sort/tuplesort.c
index 14104643e78..aff2f201f52 100644
--- a/src/backend/utils/sort/tuplesort.c
+++ b/src/backend/utils/sort/tuplesort.c
@@ -2658,7 +2658,7 @@ merge_read_buffer_size(int64 avail_mem, int nInputTapes, int nInputRuns,
 	 * we derive the input buffer size from the amount of memory available,
 	 * and M and N.
 	 */
-	return (avail_mem - TAPE_BUFFER_OVERHEAD * nOutputTapes) / nInputTapes;
+	return Max((avail_mem - TAPE_BUFFER_OVERHEAD * nOutputTapes) / nInputTapes, 0);
 }
 
 /*
-- 
2.29.2


--------------631E0A48DCAEA386819DFCEC--





^ permalink  raw  reply  [nested|flat] 22+ messages in thread

* [PATCH v3 3/3] Fix sizing of tape read buffers.
@ 2021-01-22 20:59 Heikki Linnakangas <[email protected]>
  0 siblings, 0 replies; 22+ messages in thread

From: Heikki Linnakangas @ 2021-01-22 20:59 UTC (permalink / raw)

---
 src/backend/utils/sort/tuplesort.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/backend/utils/sort/tuplesort.c b/src/backend/utils/sort/tuplesort.c
index 14104643e78..aff2f201f52 100644
--- a/src/backend/utils/sort/tuplesort.c
+++ b/src/backend/utils/sort/tuplesort.c
@@ -2658,7 +2658,7 @@ merge_read_buffer_size(int64 avail_mem, int nInputTapes, int nInputRuns,
 	 * we derive the input buffer size from the amount of memory available,
 	 * and M and N.
 	 */
-	return (avail_mem - TAPE_BUFFER_OVERHEAD * nOutputTapes) / nInputTapes;
+	return Max((avail_mem - TAPE_BUFFER_OVERHEAD * nOutputTapes) / nInputTapes, 0);
 }
 
 /*
-- 
2.29.2


--------------631E0A48DCAEA386819DFCEC--





^ permalink  raw  reply  [nested|flat] 22+ messages in thread

* [PATCH v3 3/3] Fix sizing of tape read buffers.
@ 2021-01-22 20:59 Heikki Linnakangas <[email protected]>
  0 siblings, 0 replies; 22+ messages in thread

From: Heikki Linnakangas @ 2021-01-22 20:59 UTC (permalink / raw)

---
 src/backend/utils/sort/tuplesort.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/backend/utils/sort/tuplesort.c b/src/backend/utils/sort/tuplesort.c
index 14104643e78..aff2f201f52 100644
--- a/src/backend/utils/sort/tuplesort.c
+++ b/src/backend/utils/sort/tuplesort.c
@@ -2658,7 +2658,7 @@ merge_read_buffer_size(int64 avail_mem, int nInputTapes, int nInputRuns,
 	 * we derive the input buffer size from the amount of memory available,
 	 * and M and N.
 	 */
-	return (avail_mem - TAPE_BUFFER_OVERHEAD * nOutputTapes) / nInputTapes;
+	return Max((avail_mem - TAPE_BUFFER_OVERHEAD * nOutputTapes) / nInputTapes, 0);
 }
 
 /*
-- 
2.29.2


--------------631E0A48DCAEA386819DFCEC--





^ permalink  raw  reply  [nested|flat] 22+ messages in thread

* [PATCH v3 3/3] Fix sizing of tape read buffers.
@ 2021-01-22 20:59 Heikki Linnakangas <[email protected]>
  0 siblings, 0 replies; 22+ messages in thread

From: Heikki Linnakangas @ 2021-01-22 20:59 UTC (permalink / raw)

---
 src/backend/utils/sort/tuplesort.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/backend/utils/sort/tuplesort.c b/src/backend/utils/sort/tuplesort.c
index 14104643e78..aff2f201f52 100644
--- a/src/backend/utils/sort/tuplesort.c
+++ b/src/backend/utils/sort/tuplesort.c
@@ -2658,7 +2658,7 @@ merge_read_buffer_size(int64 avail_mem, int nInputTapes, int nInputRuns,
 	 * we derive the input buffer size from the amount of memory available,
 	 * and M and N.
 	 */
-	return (avail_mem - TAPE_BUFFER_OVERHEAD * nOutputTapes) / nInputTapes;
+	return Max((avail_mem - TAPE_BUFFER_OVERHEAD * nOutputTapes) / nInputTapes, 0);
 }
 
 /*
-- 
2.29.2


--------------631E0A48DCAEA386819DFCEC--





^ permalink  raw  reply  [nested|flat] 22+ messages in thread

* [PATCH v3 3/3] Fix sizing of tape read buffers.
@ 2021-01-22 20:59 Heikki Linnakangas <[email protected]>
  0 siblings, 0 replies; 22+ messages in thread

From: Heikki Linnakangas @ 2021-01-22 20:59 UTC (permalink / raw)

---
 src/backend/utils/sort/tuplesort.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/backend/utils/sort/tuplesort.c b/src/backend/utils/sort/tuplesort.c
index 14104643e78..aff2f201f52 100644
--- a/src/backend/utils/sort/tuplesort.c
+++ b/src/backend/utils/sort/tuplesort.c
@@ -2658,7 +2658,7 @@ merge_read_buffer_size(int64 avail_mem, int nInputTapes, int nInputRuns,
 	 * we derive the input buffer size from the amount of memory available,
 	 * and M and N.
 	 */
-	return (avail_mem - TAPE_BUFFER_OVERHEAD * nOutputTapes) / nInputTapes;
+	return Max((avail_mem - TAPE_BUFFER_OVERHEAD * nOutputTapes) / nInputTapes, 0);
 }
 
 /*
-- 
2.29.2


--------------631E0A48DCAEA386819DFCEC--





^ permalink  raw  reply  [nested|flat] 22+ messages in thread

* [PATCH v3 3/3] Fix sizing of tape read buffers.
@ 2021-01-22 20:59 Heikki Linnakangas <[email protected]>
  0 siblings, 0 replies; 22+ messages in thread

From: Heikki Linnakangas @ 2021-01-22 20:59 UTC (permalink / raw)

---
 src/backend/utils/sort/tuplesort.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/backend/utils/sort/tuplesort.c b/src/backend/utils/sort/tuplesort.c
index 14104643e78..aff2f201f52 100644
--- a/src/backend/utils/sort/tuplesort.c
+++ b/src/backend/utils/sort/tuplesort.c
@@ -2658,7 +2658,7 @@ merge_read_buffer_size(int64 avail_mem, int nInputTapes, int nInputRuns,
 	 * we derive the input buffer size from the amount of memory available,
 	 * and M and N.
 	 */
-	return (avail_mem - TAPE_BUFFER_OVERHEAD * nOutputTapes) / nInputTapes;
+	return Max((avail_mem - TAPE_BUFFER_OVERHEAD * nOutputTapes) / nInputTapes, 0);
 }
 
 /*
-- 
2.29.2


--------------631E0A48DCAEA386819DFCEC--





^ permalink  raw  reply  [nested|flat] 22+ messages in thread

* [PATCH v3 3/3] Fix sizing of tape read buffers.
@ 2021-01-22 20:59 Heikki Linnakangas <[email protected]>
  0 siblings, 0 replies; 22+ messages in thread

From: Heikki Linnakangas @ 2021-01-22 20:59 UTC (permalink / raw)

---
 src/backend/utils/sort/tuplesort.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/backend/utils/sort/tuplesort.c b/src/backend/utils/sort/tuplesort.c
index 14104643e78..aff2f201f52 100644
--- a/src/backend/utils/sort/tuplesort.c
+++ b/src/backend/utils/sort/tuplesort.c
@@ -2658,7 +2658,7 @@ merge_read_buffer_size(int64 avail_mem, int nInputTapes, int nInputRuns,
 	 * we derive the input buffer size from the amount of memory available,
 	 * and M and N.
 	 */
-	return (avail_mem - TAPE_BUFFER_OVERHEAD * nOutputTapes) / nInputTapes;
+	return Max((avail_mem - TAPE_BUFFER_OVERHEAD * nOutputTapes) / nInputTapes, 0);
 }
 
 /*
-- 
2.29.2


--------------631E0A48DCAEA386819DFCEC--





^ permalink  raw  reply  [nested|flat] 22+ messages in thread

* [PATCH v3 3/3] Fix sizing of tape read buffers.
@ 2021-01-22 20:59 Heikki Linnakangas <[email protected]>
  0 siblings, 0 replies; 22+ messages in thread

From: Heikki Linnakangas @ 2021-01-22 20:59 UTC (permalink / raw)

---
 src/backend/utils/sort/tuplesort.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/backend/utils/sort/tuplesort.c b/src/backend/utils/sort/tuplesort.c
index 14104643e78..aff2f201f52 100644
--- a/src/backend/utils/sort/tuplesort.c
+++ b/src/backend/utils/sort/tuplesort.c
@@ -2658,7 +2658,7 @@ merge_read_buffer_size(int64 avail_mem, int nInputTapes, int nInputRuns,
 	 * we derive the input buffer size from the amount of memory available,
 	 * and M and N.
 	 */
-	return (avail_mem - TAPE_BUFFER_OVERHEAD * nOutputTapes) / nInputTapes;
+	return Max((avail_mem - TAPE_BUFFER_OVERHEAD * nOutputTapes) / nInputTapes, 0);
 }
 
 /*
-- 
2.29.2


--------------631E0A48DCAEA386819DFCEC--





^ permalink  raw  reply  [nested|flat] 22+ messages in thread

* [PATCH v3 3/3] Fix sizing of tape read buffers.
@ 2021-01-22 20:59 Heikki Linnakangas <[email protected]>
  0 siblings, 0 replies; 22+ messages in thread

From: Heikki Linnakangas @ 2021-01-22 20:59 UTC (permalink / raw)

---
 src/backend/utils/sort/tuplesort.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/backend/utils/sort/tuplesort.c b/src/backend/utils/sort/tuplesort.c
index 14104643e78..aff2f201f52 100644
--- a/src/backend/utils/sort/tuplesort.c
+++ b/src/backend/utils/sort/tuplesort.c
@@ -2658,7 +2658,7 @@ merge_read_buffer_size(int64 avail_mem, int nInputTapes, int nInputRuns,
 	 * we derive the input buffer size from the amount of memory available,
 	 * and M and N.
 	 */
-	return (avail_mem - TAPE_BUFFER_OVERHEAD * nOutputTapes) / nInputTapes;
+	return Max((avail_mem - TAPE_BUFFER_OVERHEAD * nOutputTapes) / nInputTapes, 0);
 }
 
 /*
-- 
2.29.2


--------------631E0A48DCAEA386819DFCEC--





^ permalink  raw  reply  [nested|flat] 22+ messages in thread

* [PATCH v3 3/3] Fix sizing of tape read buffers.
@ 2021-01-22 20:59 Heikki Linnakangas <[email protected]>
  0 siblings, 0 replies; 22+ messages in thread

From: Heikki Linnakangas @ 2021-01-22 20:59 UTC (permalink / raw)

---
 src/backend/utils/sort/tuplesort.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/backend/utils/sort/tuplesort.c b/src/backend/utils/sort/tuplesort.c
index 14104643e78..aff2f201f52 100644
--- a/src/backend/utils/sort/tuplesort.c
+++ b/src/backend/utils/sort/tuplesort.c
@@ -2658,7 +2658,7 @@ merge_read_buffer_size(int64 avail_mem, int nInputTapes, int nInputRuns,
 	 * we derive the input buffer size from the amount of memory available,
 	 * and M and N.
 	 */
-	return (avail_mem - TAPE_BUFFER_OVERHEAD * nOutputTapes) / nInputTapes;
+	return Max((avail_mem - TAPE_BUFFER_OVERHEAD * nOutputTapes) / nInputTapes, 0);
 }
 
 /*
-- 
2.29.2


--------------631E0A48DCAEA386819DFCEC--





^ permalink  raw  reply  [nested|flat] 22+ messages in thread

* [PATCH v3 3/3] Fix sizing of tape read buffers.
@ 2021-01-22 20:59 Heikki Linnakangas <[email protected]>
  0 siblings, 0 replies; 22+ messages in thread

From: Heikki Linnakangas @ 2021-01-22 20:59 UTC (permalink / raw)

---
 src/backend/utils/sort/tuplesort.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/backend/utils/sort/tuplesort.c b/src/backend/utils/sort/tuplesort.c
index 14104643e78..aff2f201f52 100644
--- a/src/backend/utils/sort/tuplesort.c
+++ b/src/backend/utils/sort/tuplesort.c
@@ -2658,7 +2658,7 @@ merge_read_buffer_size(int64 avail_mem, int nInputTapes, int nInputRuns,
 	 * we derive the input buffer size from the amount of memory available,
 	 * and M and N.
 	 */
-	return (avail_mem - TAPE_BUFFER_OVERHEAD * nOutputTapes) / nInputTapes;
+	return Max((avail_mem - TAPE_BUFFER_OVERHEAD * nOutputTapes) / nInputTapes, 0);
 }
 
 /*
-- 
2.29.2


--------------631E0A48DCAEA386819DFCEC--





^ permalink  raw  reply  [nested|flat] 22+ messages in thread

* [PATCH v3 3/3] Fix sizing of tape read buffers.
@ 2021-01-22 20:59 Heikki Linnakangas <[email protected]>
  0 siblings, 0 replies; 22+ messages in thread

From: Heikki Linnakangas @ 2021-01-22 20:59 UTC (permalink / raw)

---
 src/backend/utils/sort/tuplesort.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/backend/utils/sort/tuplesort.c b/src/backend/utils/sort/tuplesort.c
index 14104643e78..aff2f201f52 100644
--- a/src/backend/utils/sort/tuplesort.c
+++ b/src/backend/utils/sort/tuplesort.c
@@ -2658,7 +2658,7 @@ merge_read_buffer_size(int64 avail_mem, int nInputTapes, int nInputRuns,
 	 * we derive the input buffer size from the amount of memory available,
 	 * and M and N.
 	 */
-	return (avail_mem - TAPE_BUFFER_OVERHEAD * nOutputTapes) / nInputTapes;
+	return Max((avail_mem - TAPE_BUFFER_OVERHEAD * nOutputTapes) / nInputTapes, 0);
 }
 
 /*
-- 
2.29.2


--------------631E0A48DCAEA386819DFCEC--





^ permalink  raw  reply  [nested|flat] 22+ messages in thread

* [PATCH v3 3/3] Fix sizing of tape read buffers.
@ 2021-01-22 20:59 Heikki Linnakangas <[email protected]>
  0 siblings, 0 replies; 22+ messages in thread

From: Heikki Linnakangas @ 2021-01-22 20:59 UTC (permalink / raw)

---
 src/backend/utils/sort/tuplesort.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/backend/utils/sort/tuplesort.c b/src/backend/utils/sort/tuplesort.c
index 14104643e78..aff2f201f52 100644
--- a/src/backend/utils/sort/tuplesort.c
+++ b/src/backend/utils/sort/tuplesort.c
@@ -2658,7 +2658,7 @@ merge_read_buffer_size(int64 avail_mem, int nInputTapes, int nInputRuns,
 	 * we derive the input buffer size from the amount of memory available,
 	 * and M and N.
 	 */
-	return (avail_mem - TAPE_BUFFER_OVERHEAD * nOutputTapes) / nInputTapes;
+	return Max((avail_mem - TAPE_BUFFER_OVERHEAD * nOutputTapes) / nInputTapes, 0);
 }
 
 /*
-- 
2.29.2


--------------631E0A48DCAEA386819DFCEC--





^ permalink  raw  reply  [nested|flat] 22+ messages in thread

* [PATCH v3 3/3] Fix sizing of tape read buffers.
@ 2021-01-22 20:59 Heikki Linnakangas <[email protected]>
  0 siblings, 0 replies; 22+ messages in thread

From: Heikki Linnakangas @ 2021-01-22 20:59 UTC (permalink / raw)

---
 src/backend/utils/sort/tuplesort.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/backend/utils/sort/tuplesort.c b/src/backend/utils/sort/tuplesort.c
index 14104643e78..aff2f201f52 100644
--- a/src/backend/utils/sort/tuplesort.c
+++ b/src/backend/utils/sort/tuplesort.c
@@ -2658,7 +2658,7 @@ merge_read_buffer_size(int64 avail_mem, int nInputTapes, int nInputRuns,
 	 * we derive the input buffer size from the amount of memory available,
 	 * and M and N.
 	 */
-	return (avail_mem - TAPE_BUFFER_OVERHEAD * nOutputTapes) / nInputTapes;
+	return Max((avail_mem - TAPE_BUFFER_OVERHEAD * nOutputTapes) / nInputTapes, 0);
 }
 
 /*
-- 
2.29.2


--------------631E0A48DCAEA386819DFCEC--





^ permalink  raw  reply  [nested|flat] 22+ messages in thread

* Re: Detach shared memory in Postmaster child if not needed
@ 2024-07-29 11:44 Aleksander Alekseev <[email protected]>
  0 siblings, 0 replies; 22+ messages in thread

From: Aleksander Alekseev @ 2024-07-29 11:44 UTC (permalink / raw)
  To: pgsql-hackers; +Cc: Rui Zhao <[email protected]>; hlinnaka <[email protected]>; robertmhaas <[email protected]>; tgl <[email protected]>

Hi Rui,

> Prior to PG16, postmaster children would manually detach from shared memory
> if it was not needed. However, this behavior was removed in fork mode in
> commit aafc05d.
>
> Detaching shared memory when it is no longer needed is beneficial, as
> postmaster children (like syslogger) don't wish to take any risk of
> accidentally corrupting shared memory. Additionally, any panic in these
> processes will not reset shared memory.
>
> The attached patch addresses this issue by detaching shared memory after
> fork_process().

Thanks for the patch. How do you estimate its performance impact?

Note the comments for postmaster_child_launch(). This function is
exposed to the third-party code and guarantees to attach shared
memory. I doubt that there is much third-party code in existence to
break but you should change to comment.

-- 
Best regards,
Aleksander Alekseev






^ permalink  raw  reply  [nested|flat] 22+ messages in thread


end of thread, other threads:[~2024-07-29 11:44 UTC | newest]

Thread overview: 22+ messages (download: mbox mbox.gz follow: Atom feed)
-- links below jump to the message on this page --
2021-01-22 20:59 [PATCH v3 3/3] Fix sizing of tape read buffers. Heikki Linnakangas <[email protected]>
2021-01-22 20:59 [PATCH v3 3/3] Fix sizing of tape read buffers. Heikki Linnakangas <[email protected]>
2021-01-22 20:59 [PATCH v3 3/3] Fix sizing of tape read buffers. Heikki Linnakangas <[email protected]>
2021-01-22 20:59 [PATCH v3 3/3] Fix sizing of tape read buffers. Heikki Linnakangas <[email protected]>
2021-01-22 20:59 [PATCH v3 3/3] Fix sizing of tape read buffers. Heikki Linnakangas <[email protected]>
2021-01-22 20:59 [PATCH v3 3/3] Fix sizing of tape read buffers. Heikki Linnakangas <[email protected]>
2021-01-22 20:59 [PATCH v3 3/3] Fix sizing of tape read buffers. Heikki Linnakangas <[email protected]>
2021-01-22 20:59 [PATCH v3 3/3] Fix sizing of tape read buffers. Heikki Linnakangas <[email protected]>
2021-01-22 20:59 [PATCH v3 3/3] Fix sizing of tape read buffers. Heikki Linnakangas <[email protected]>
2021-01-22 20:59 [PATCH v3 3/3] Fix sizing of tape read buffers. Heikki Linnakangas <[email protected]>
2021-01-22 20:59 [PATCH v3 3/3] Fix sizing of tape read buffers. Heikki Linnakangas <[email protected]>
2021-01-22 20:59 [PATCH v3 3/3] Fix sizing of tape read buffers. Heikki Linnakangas <[email protected]>
2021-01-22 20:59 [PATCH v3 3/3] Fix sizing of tape read buffers. Heikki Linnakangas <[email protected]>
2021-01-22 20:59 [PATCH v3 3/3] Fix sizing of tape read buffers. Heikki Linnakangas <[email protected]>
2021-01-22 20:59 [PATCH v3 3/3] Fix sizing of tape read buffers. Heikki Linnakangas <[email protected]>
2021-01-22 20:59 [PATCH v3 3/3] Fix sizing of tape read buffers. Heikki Linnakangas <[email protected]>
2021-01-22 20:59 [PATCH v3 3/3] Fix sizing of tape read buffers. Heikki Linnakangas <[email protected]>
2021-01-22 20:59 [PATCH v3 3/3] Fix sizing of tape read buffers. Heikki Linnakangas <[email protected]>
2021-01-22 20:59 [PATCH v3 3/3] Fix sizing of tape read buffers. Heikki Linnakangas <[email protected]>
2021-01-22 20:59 [PATCH v3 3/3] Fix sizing of tape read buffers. Heikki Linnakangas <[email protected]>
2021-01-22 20:59 [PATCH v3 3/3] Fix sizing of tape read buffers. Heikki Linnakangas <[email protected]>
2024-07-29 11:44 Re: Detach shared memory in Postmaster child if not needed Aleksander Alekseev <[email protected]>

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