summaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorStephane Marchesin <stephane.marchesin@gmail.com>2012-03-15 00:39:48 -0700
committerStephane Marchesin <stephane.marchesin@gmail.com>2012-03-15 00:39:48 -0700
commit83d5fae85ad9d960c4967a6091b7019cdefac639 (patch)
tree55dac3b3a913c417368c7e3ad6b35f87cad87812
parentc79e2d605fa16166adf9103acfde55ebf25c36a7 (diff)
Small changes.
-rw-r--r--linuxgraphicsdrivers.lyx33
1 files changed, 17 insertions, 16 deletions
diff --git a/linuxgraphicsdrivers.lyx b/linuxgraphicsdrivers.lyx
index d0ebe6e..f522b60 100644
--- a/linuxgraphicsdrivers.lyx
+++ b/linuxgraphicsdrivers.lyx
@@ -709,13 +709,13 @@ The first user of the bus is the CPU.
In particular, a peripheral which has the ability to read and write to
memory without the CPU intervention is said to be DMA (Direct Memory Access)
capable, and the memory transaction is usually called a DMA.
- This type of transaction is interesting, because it allows the driver to use
- the GPU instead of the CPU to do memory transfers.
- Since the CPU doesn't need to actively work any more to achieve those transfers,
- and since it allows better asynchronicity between the CPU and the GPU,
+ This type of transaction is interesting, because it allows the driver to
+ use the GPU instead of the CPU to do memory transfers.
+ Since the CPU doesn't need to actively work any more to achieve those transfers
+, and since it allows better asynchronicity between the CPU and the GPU,
better performance can be attained.
- Common uses of DMA include improving the performance of
- texture uploads or streaming video.
+ Common uses of DMA include improving the performance of texture uploads
+ or streaming video.
Today, all graphics processors feature this ability (named DMA bus mastering)
which consists in the card requesting and subsequently taking control of
the bus for a number of microseconds.
@@ -737,11 +737,11 @@ Notice that the DMA capability can be a downside in some cases.
For example on real time systems, this means the CPU is unable to access
the bus while a DMA transaction is in progress, and since DMA transactions
happen asynchronously this can lead to missing a real time scheduling deadline.
- Another example is small DMA memory transfers, where the CPU overhead of setting
- up the DMA is greater than the gain in asynchronicity and therefore transfers
- slow down.
- So while DMA has a lot of advantages from a performance viewpoint,
- there are situations where it should be avoided.
+ Another example is small DMA memory transfers, where the CPU overhead of
+ setting up the DMA is greater than the gain in asynchronicity and therefore
+ transfers slow down.
+ So while DMA has a lot of advantages from a performance viewpoint, there
+ are situations where it should be avoided.
\end_layout
\begin_layout Section
@@ -1441,10 +1441,10 @@ Virtual memory.
\lang english
In order to simplify programming, it is easier to handle contiguous memory
areas.
- This is easy to achieve as long as only a small area is needed.
- But allocating a bigger memory chunk would require as much contiguous physical
- memory which is difficult if not impossible to achieve shortly after bootup
- because of memory fragmentation.
+ It is easy to allocate a small contiguous area, but allocating a bigger
+ memory chunk would require as much contiguous physical memory which is
+ difficult if not impossible to achieve shortly after bootup because of
+ memory fragmentation.
Therefore, a mechanism is required to keep the appearance of a contiguous
piece of memory to the application while using scattered pieces.
@@ -1890,7 +1890,8 @@ clflush
\begin_layout Standard
\lang english
-There are 3 caching modes, usable both through MTRR and PAT on system memory:
+There are three caching modes, usable both through MTRRs and PAT on system
+ memory:
\end_layout
\begin_layout Itemize