Re: [PATCH v4 3/3] squashfs: implement readahead

[Hsin-Yi Wang]

On Fri, Jun 3, 2022 at 10:10 PM Marek Szyprowski
<m.szyprowski@xxxxxxxxxxx> wrote:
>
> Hi Matthew,
>
> On 03.06.2022 14:59, Matthew Wilcox wrote:
> > On Fri, Jun 03, 2022 at 02:54:21PM +0200, Marek Szyprowski wrote:
> >> On 01.06.2022 12:39, Hsin-Yi Wang wrote:
> >>> Implement readahead callback for squashfs. It will read datablocks
> >>> which cover pages in readahead request. For a few cases it will
> >>> not mark page as uptodate, including:
> >>> - file end is 0.
> >>> - zero filled blocks.
> >>> - current batch of pages isn't in the same datablock or not enough in a
> >>>     datablock.
> >>> - decompressor error.
> >>> Otherwise pages will be marked as uptodate. The unhandled pages will be
> >>> updated by readpage later.
> >>>
> >>> Suggested-by: Matthew Wilcox <willy@xxxxxxxxxxxxx>
> >>> Signed-off-by: Hsin-Yi Wang <hsinyi@xxxxxxxxxxxx>
> >>> Reported-by: Matthew Wilcox <willy@xxxxxxxxxxxxx>
> >>> Reported-by: Phillip Lougher <phillip@xxxxxxxxxxxxxxx>
> >>> Reported-by: Xiongwei Song <Xiongwei.Song@xxxxxxxxxxxxx>
> >>> ---
> >> This patch landed recently in linux-next as commit 95f7a26191de
> >> ("squashfs: implement readahead"). I've noticed that it causes serious
> >> issues on my test systems (various ARM 32bit and 64bit based boards).
> >> The easiest way to observe is udev timeout 'waiting for /dev to be fully
> >> populated' and prolonged booting time. I'm using squashfs for deploying
> >> kernel modules via initrd. Reverting aeefca9dfae7 & 95f7a26191deon on
> >> top of the next-20220603 fixes the issue.
> > How large are these files?  Just a few kilobytes?
>
> Yes, they are small, most of them are smaller than 16KB, some about
> 128KB and a few about 256KB. I've sent a detailed list in private mail.
>

Hi Marek,

Are there any obvious squashfs errors in dmesg? Did you enable
CONFIG_SQUASHFS_FILE_DIRECT or CONFIG_SQUASHFS_FILE_CACHE?

Thanks

> Best regards
> --
> Marek Szyprowski, PhD
> Samsung R&D Institute Poland
>