On Tue, Mar 13, 2012 at 01:04:58PM -0400, Martin K. Petersen wrote: > >>>>> "Vivek" == Vivek Goyal <vgoyal@xxxxxxxxxx> writes: > > Vivek> On Mon, Mar 12, 2012 at 11:04:18AM +0800, Shaohua Li wrote: > >> In raid 0 case, a big discard request is divided into several small > >> requests in chunk_size unit. Such requests can be merged in low layer > >> if we have correct plug added. This should improve the performance a > >> little bit. > > Vivek> Martin posted a patch to remove the support for allowing merging > Vivek> of discard requests. But this seems to be a reasonable use case > Vivek> for allowing mering discard requests. CCing Martin. > > Merging discard requests is hard given how we need to prepare the > command payload at the bottom of the stack. The current upstream merge > code pretends to be working but it actually doesn't. That's why I want > it dead and buried. > > I have some changes pending (that I need for the REQ_COPY support) that > will make merging of non-rw requests easier to deal with. But that's a > kernel release cycle away... So first we will get rid of mering discard request and then enable after one release cycle once REQ_COPY support is in? Thanks Vivek -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
