Hi,
On Sat, Feb 12, 2011 at 08:25, Willy Tarreau <[email protected]> wrote:
> On Fri, Feb 11, 2011 at 11:11:04PM +0100, Przemyslaw Pawelczyk wrote:
>> Please consider applying below patch to 2.6.32 tree (it's already in
>> 2.6.33+).
>>
>> There is many a box using this longterm rel, so it would undoubtedly help in
>> levaraging improved sendfile() usability world-wide.
>
> I'm seeing that it could be applied to 2.6.27 too (which has the same code)
> but what I don't get is what it will improve. Are there currently situations
> where 2.6.27 or 2.6.32 fail with sendfile that will not fail anymore with
> this patch ?
In the good old days (2.4 and before) sendfile()'s out_fd could refer
to a regular file. Pretty convenient and efficient way of copying data
between files. This patch brings it back. I bet a lot of people missed
reintroduction of this great sendfile() feature. Presumably because:
(1) it's not mentioned in the subject, (2) it's mentioned in the
message though, but as a side effect and without proper stress, (3)
it's not obvious after skimming through the code (without the
message). After all we all like such side effects.
Applying it (in full-form) to 2.6.27 requires actually additional
changes, e.g. there is no default_file_splice_{read,write}()
functions. So I'm not sure it should be done in 2.6.27.
Regards.
P.S. When I noticed this sendfile() "enhancement" I was going to send
a patch to linux-man, but Akira Fujita did it 2 weeks ago. Still, one
year has passed...
--
Przemysław Pawełczyk
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