880435 - readahead is implemented suboptimally on linux

Status: RESOLVED FIXED

(Core :: General, defect)

Description

[(dormant account)]

if (flags & OS_READAHEAD) {
        readahead(PR_FileDesc2NativeHandle(*_retval), 0, 0);
    }

it should using fadvise(FADV_SEQUENTIAL)

Comment 1

[(No longer employed by Mozilla) Aaron Klotz]

Attachment: Patch v1

Simple patch.

Comment 2

[Mike Hommey [:glandium]]

Comment on attachment 763694 [details] [diff] [review]
Patch v1

Review of attachment 763694 [details] [diff] [review]:
-----------------------------------------------------------------

::: xpcom/io/nsLocalFileUnix.cpp
@@ +401,5 @@
>  
>  #if defined(LINUX) && !defined(ANDROID)
>      if (flags & OS_READAHEAD) {
> +        posix_fadvise(PR_FileDesc2NativeHandle(*_retval), 0, 0,
> +                      POSIX_FADV_SEQUENTIAL);

For files that are read sequentially, that would work, but for libraries, it would make things worse.

Comment 3

[Mike Hommey [:glandium]]

Comment on attachment 763694 [details] [diff] [review]
Patch v1

Review of attachment 763694 [details] [diff] [review]:
-----------------------------------------------------------------

Oh wait, that's not the code shared with library loading.

Comment 4

[(No longer employed by Mozilla) Aaron Klotz]

Try:
https://tbpl.mozilla.org/?tree=Try&rev=b99adcace0cd

https://hg.mozilla.org/integration/mozilla-inbound/rev/4eb19eba16ea

Comment 5

[Ed Morley [:emorley]]

https://hg.mozilla.org/mozilla-central/rev/4eb19eba16ea