Update generated RST

parent 8f72a7ed
......@@ -269,9 +269,11 @@ memory overhead.
The *size* argument will be rounded down to a multiple of the
(possibly rounded) *minpage* argument.
In addition to the configured memory, approximately 1 / ( *minpage* *
8) bytes are required for metadata (bitmaps). For the default
*minpage* of 64 Bytes, this amounts to approximately 0.2%.
Besides the configured memory size, approximately 1 / ( *minpage* *
4) of it is additionally required for metadata (bitmaps) in the
varnish home directory and in memory. For the default *minpage* of 64
Bytes, this amounts to approximately 0.4%. The actual figure is output
at startup as ``buddy: metadata (bitmap) size``.
This storage can *not* be used via ``storage.``\ *<name>*.
......@@ -448,6 +450,13 @@ On Linux, the memory cache will be allocated from huge pages, if
available and if *memsize* is larger than a huge page. *memsize* will
then be rounded up to a multiple of the respective huge page size.
Besides the configured memory cache size, approximately 1 / 256 (0.4%)
of *memsize* plus 1 / 16384 (0.006%) of *dsksize* will be required in
the varnish home directory and in memory. For example, for
``dsksize=1t`` and ``memsize=1g``, this amounts to roughly 70MB. The
actual figures are output at startup as ``fellow: metadata (bitmap)
memory``.
*objsize_hint* (default 256KB) is used to sanity check *memsize* in
relation to *dsksize*. It should be set to a value lower than the
average object size (actual or expected). If *memsize* is configured
......@@ -870,7 +879,9 @@ FELLOW KNOWN ISSUES
* On Linux with ``io_uring``, by default, `fellow` registers all of
the memory cache as buffers using
:ref:`io_uring_register_buffers(3)` to achieve optimal performance
at runtime, if supported by the system.
at runtime, if supported by the system. Where supported, this
enables *zero-copy* IO, where the hardware performs DMA directly
into the `fellow` memory cache.
Buffer registrations happen in multiple threads in parallel, one for
each io ring.
......@@ -890,6 +901,9 @@ FELLOW KNOWN ISSUES
registration is forced to be done as serial, syncronous registration
operations.
Note that even with registered buffers, ``io_uring`` has nothing to
do with how the `fellow` memory cache and LRU on it work.
* If initialization takes longer than the :ref:`varnishd(1)`
``cli_timeout``, it might not come up properly in that it does not
accept connections after finishing storage initialization. To avoid
......
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