Redfs ubuntu noble writethrough split#183
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Signed-off-by: Horst Birthelmer <hbirthelmer@ddn.com>
bsbernd
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| * for them. Unaligned writes keep using the writeback cache, where they | ||
| * can merge with neighbouring data. | ||
| */ | ||
| static bool fuse_use_writeback_cache(struct fuse_conn *fc, struct kiocb *iocb, |
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How about for the small aligned write, such as 4K, 8K, what if we have a threshold, which is our bucket size (2M), if aligned, but less than 2M, still do write-back cache?
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yes ... still writeback... in the hope that more writes will be done and we can write alogned later. If during this delay, we get a flush or invalidate, than we haven't lost anything
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when fc->big_writes will true?
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this is a parameter from the fuse server
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if it is false FUSE will write every page separately
Writes that already match the alignment advertised via FUSE_ALIGN_PG_ORDER gain nothing from the writeback cache and can degrade into page-sized WRITE requests under dirty throttling. Send them through fuse_perform_write() instead, which packs requests up to max_write and keeps them stripe-aligned for the backend. They create no dirty pages, so no DLM write lock needs to be cached for them. Unaligned writes keep using the writeback cache. Also clarify in the uapi header that align_page_order is the log2 of the alignment in bytes, not in pages. Signed-off-by: Horst Birthelmer <hbirthelmer@ddn.com>
Add a per-connection size threshold, settable via fusectl as writethrough_threshold, that sends buffered writes >= threshold through fuse_perform_write() regardless of alignment. The knob is off by default (0 == disabled) and leaves the existing alignment-based decision in place for writes below the threshold. Signed-off-by: Horst Birthelmer <hbirthelmer@ddn.com>
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