pub fn pread_uncached(file: &File, offset: u64, dst: &mut [u8]) -> Result<()>Expand description
pread, then drop the range from the page cache: the bytes now live in
the arena and the cache copy is dead weight. With a 100 GiB page-locked
arena on a 121 GiB Spark, leaving 12 MiB of cache behind every miss made
the kernel reclaim into swap in the middle of a step (single steps of 2 to
18 s on the 09-19 standard). ATLAS_DS41_KEEP_PAGE_CACHE=1 keeps the old
behaviour.