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Now there is only one launcher. Which means it can be used to start kitty with profiling and ASAN in the natural way. The recommended way to run kitty from source is now: ./kitty/launcher/kitty The launcher also automatically re-execs to resolve symlinks on macOS.
60 lines
2.7 KiB
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60 lines
2.7 KiB
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|kitty| Performance
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===================
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The main goals for |kitty| performance are user perceived latency while typing
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and "smoothness" while scrolling as well as CPU usage. |kitty| tries hard to find
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an optimum balance for these. To that end it keeps a cache of each rendered
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glyph in video RAM so that font rendering is not a bottleneck. Interaction
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with child programs takes place in a separate thread from rendering, to improve
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smoothness.
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There are two parameters you can tune to adjust the performance. :opt:`repaint_delay`
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and :opt:`input_delay`. These control the artificial delays introduced into the
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render loop to reduce CPU usage. See :ref:`conf-kitty-performance` for details.
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See also the :opt:`sync_to_monitor` option to further decrease latency at the cost
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of some `tearing <https://en.wikipedia.org/wiki/Screen_tearing>`_ while scrolling.
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You can generate detailed per-function performance data using `gperftools
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<https://github.com/gperftools/gperftools>`_. Build |kitty| with `make
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profile`. Run kitty and perform the task you want to analyse, for example,
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scrolling a large file with `less`. After you quit, function call statistics
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will be printed to `stdout` and you can use tools like *kcachegrind* for more
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detailed analysis.
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Here are some CPU usage numbers for the task of scrolling a file continuously
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in less. The CPU usage is for the terminal process and X together and is
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measured using htop. The measurements are taken at the same font and window
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size for all terminals on a ``Intel(R) Core(TM) i7-4820K CPU @ 3.70GHz`` CPU
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with a ``Advanced Micro Devices, Inc. [AMD/ATI] Cape Verde XT [Radeon HD
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7770/8760 / R7 250X]`` GPU.
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============== =========================
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Terminal CPU usage (X + terminal)
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============== =========================
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|kitty| 6 - 8%
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xterm 5 - 7% (but scrolling was extremely janky)
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termite 10 - 13%
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urxvt 12 - 14%
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gnome-terminal 15 - 17%
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konsole 29 - 31%
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============== =========================
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As you can see, |kitty| uses much less CPU than all terminals, except xterm, but
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its scrolling "smoothness" is much better than that of xterm (at least to my,
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admittedly biased, eyes).
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.. _perf-cat:
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.. note::
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Some people have asked why kitty does not perform better than terminal XXX in
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the test of sinking large amounts of data, such as catting a large text
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file. The answer is because this is not a goal for kitty. kitty
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deliberately throttles input parsing and output rendering to minimize
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resource usage while still being able to sink output faster than any real
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world program can produce it. Reducing CPU usage, and hence battery drain
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while achieving instant response times and smooth scrolling to a human eye
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is a far more important goal.
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