On Tue 25-06-24 14:28:34, zippermonkey wrote: > To illustrate this problem, I created the following example: > > Assuming that the process reads sequentially from the beginning of the file > and > calls the `page_cache_sync_readahead` function. In this sync readahead > function, > since the index is 0, it will proceed to `initial_readahead` and initialize > `ra_state`. It allocates a folio with an order of 2 and marks it as > PG_readahead. > Next, because` (folio_test_readahead(folio))` is true, the > page_cache_async_ra > function is called, which causes the `ra_state` to be initialized again. Good spotting guys! There are actually more problems in the readahead code. I have just pushed out a patch series [1] addressing several issues that should also address the problem you've found. Can you please test whether it provides a similar speedup as your fix (sorry, I forgot to CC you on the series)? Thanks! [1] https://lore.kernel.org/20240625100859.15507-1-jack@xxxxxxx Honza -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR
