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From: "Yordan Karadzhov (VMware)" <y.karadz@gmail.com>
To: rostedt@goodmis.org
Cc: linux-trace-devel@vger.kernel.org,
	"Yordan Karadzhov (VMware)" <y.karadz@gmail.com>
Subject: [PATCH v2 02/20] kernel-shark: Use only signed types in kshark_entry
Date: Mon, 12 Oct 2020 16:35:05 +0300
Message-ID: <20201012133523.469040-3-y.karadz@gmail.com> (raw)
In-Reply-To: <20201012133523.469040-1-y.karadz@gmail.com>

Using uint64_t for the value of the offset was just wrong. According
to the POSIX standard off_t is a signed integer type with unspecified
size. Here we stick to a 64 bit integer, because this size guaranties
optimal packing of the kshark_entry structure.

Using unsigned values for the timestamps is also a source of problems
and has been a reason for the introduction of multiple bugs in the past.
In principal the value of the timestamps cannot be negative. However,
this value must have the same type as the values used to define the
state of the visualization model, like the range of the model or the
size of the bin. The model state definitions should not take negative
values as well, however their values are recalculated automatically when
the user browses the data and those calculations may result in negative
values in some corner cases. Because of this it is better to use a
signed integer type and treat the negative values as an indicator
of an error rather than have the negative result of the calculations
casted into unsigned type which results into unpredictable behavior of
the model.

Signed-off-by: Yordan Karadzhov (VMware) <y.karadz@gmail.com>
---
 src/libkshark.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/libkshark.h b/src/libkshark.h
index 0d6c50d1..9eecc2d0 100644
--- a/src/libkshark.h
+++ b/src/libkshark.h
@@ -61,7 +61,7 @@ struct kshark_entry {
 	int32_t		event_id;
 
 	/** The offset into the trace file, used to find the record. */
-	uint64_t	offset;
+	int64_t		offset;
 
 	/**
 	 * The time of the record in nano seconds. The value is taken from
@@ -69,7 +69,7 @@ struct kshark_entry {
 	 * dependent. The time usually is the timestamp from when the system
 	 * started.
 	 */
-	uint64_t	ts;
+	int64_t		ts;
 };
 
 /** Size of the task's hash table. */
-- 
2.25.1


  parent reply index

Thread overview: 47+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-12 13:35 [PATCH v2 00/20] Start KernelShark v2 transformation Yordan Karadzhov (VMware)
2020-10-12 13:35 ` [PATCH v2 01/20] kernel-shark: Start introducing KernelShark 2.0 Yordan Karadzhov (VMware)
2020-10-12 13:35 ` Yordan Karadzhov (VMware) [this message]
2020-10-12 13:35 ` [PATCH v2 03/20] kernel-shark: Introduce libkshark-hash Yordan Karadzhov (VMware)
2020-10-12 14:05   ` Steven Rostedt
2020-10-12 14:05     ` Steven Rostedt
2020-10-12 14:18       ` Yordan Karadzhov (VMware)
2020-10-12 13:35 ` [PATCH v2 04/20] kernel-shark: Introduce Data streams Yordan Karadzhov (VMware)
2020-10-12 13:35 ` [PATCH v2 05/20] kernel-shark: Add stream_id to kshark_entry Yordan Karadzhov (VMware)
2020-10-13  0:05   ` Steven Rostedt
2020-10-29 10:08     ` Yordan Karadzhov (VMware)
2020-10-12 13:35 ` [PATCH v2 06/20] kernel-shark: Rename static methods in libkshark Yordan Karadzhov (VMware)
2020-10-12 13:35 ` [PATCH v2 07/20] kernel-shark: Add basic methods for Data streams Yordan Karadzhov (VMware)
2020-10-13  0:18   ` Steven Rostedt
2020-10-29 10:10     ` Yordan Karadzhov (VMware)
2020-10-29 14:04       ` Steven Rostedt
2020-10-29 14:49         ` Yordan Karadzhov (VMware)
2020-10-30  1:57           ` Steven Rostedt
2020-11-03 13:38             ` Yordan Karadzhov (VMware)
2020-11-04 15:41               ` Steven Rostedt
2020-11-05 14:35                 ` Yordan Karadzhov (VMware)
2020-10-12 13:35 ` [PATCH v2 08/20] kernel-shark: Housekeeping before implementing stream interface Yordan Karadzhov (VMware)
2020-10-12 13:35 ` [PATCH v2 09/20] kernel-shark: Add stream interface for trace-cmd data Yordan Karadzhov (VMware)
2020-10-13  0:44   ` Steven Rostedt
2020-10-29 11:16     ` Yordan Karadzhov (VMware)
2020-10-12 13:35 ` [PATCH v2 10/20] kernel-shark: Start using data streams Yordan Karadzhov (VMware)
2020-10-14 18:56   ` Steven Rostedt
2020-11-05 14:58     ` Yordan Karadzhov (VMware)
2020-11-05 18:17       ` Steven Rostedt
2020-11-06 14:31         ` Yordan Karadzhov (VMware)
2020-11-06 15:18           ` Steven Rostedt
2020-11-09 14:49             ` Yordan Karadzhov (VMware)
2020-10-12 13:35 ` [PATCH v2 11/20] kernel-shark: Remove dead code Yordan Karadzhov (VMware)
2020-10-12 13:35 ` [PATCH v2 12/20] kernel-shark: Redesign the plugin interface Yordan Karadzhov (VMware)
2020-10-14 21:09   ` Steven Rostedt
2020-10-12 13:35 ` [PATCH v2 13/20] kernel-shark: Complete the stream integration Yordan Karadzhov (VMware)
2020-10-14 23:52   ` Steven Rostedt
2020-10-12 13:35 ` [PATCH v2 14/20] kernel-shark: Provide merging of multiple data streams Yordan Karadzhov (VMware)
2020-10-12 13:35 ` [PATCH v2 15/20] kernel-shark: Integrate the stream definitions with data model Yordan Karadzhov (VMware)
2020-10-12 13:35 ` [PATCH v2 16/20] kernel-shark: Use only signed types for model defs Yordan Karadzhov (VMware)
2020-10-12 13:35 ` [PATCH v2 17/20] kernel-shark: Add ksmodel_get_bin() Yordan Karadzhov (VMware)
2020-10-12 13:35 ` [PATCH v2 18/20] kernel-shark: Protect ksmodel_set_in_range_bining() Yordan Karadzhov (VMware)
2020-10-12 13:35 ` [PATCH v2 19/20] kernel-shark: Add methods for time calibration Yordan Karadzhov (VMware)
2020-10-12 13:35 ` [PATCH v2 20/20] kernel-shark: Integrate streams with libkshark-configio Yordan Karadzhov (VMware)
2020-11-05 19:22   ` Steven Rostedt
2020-11-09 14:55     ` Yordan Karadzhov (VMware)
2020-11-09 15:28       ` Steven Rostedt

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