Date: Fri, 15 Sep 2017 22:40:57 +0000 (UTC) From: John Baldwin <jhb@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r323630 - head/sys/dev/cxgbe/tom Message-ID: <201709152240.v8FMevvt009106@repo.freebsd.org>
next in thread | raw e-mail | index | archive | help
Author: jhb Date: Fri Sep 15 22:40:57 2017 New Revision: 323630 URL: https://svnweb.freebsd.org/changeset/base/323630 Log: Avoid reusing the wrong buffer for a DDP AIO request. To optimize the case of ping-ponging between two buffers, the DDP code caches the last two buffers used keeping the pages wired and page pods stored in the NIC's RAM. If a new aio_read() request uses one of the same buffers, then the work of holding pages, etc. can be avoided. However, the starting virtual address of an aio buffer was not saved, only the page count, length, and initial page offset. Thus, an aio_read() request could match a different buffer in the address space. (Earlier during development vm_fault_hold_quick_pages() was always called and the vm_page_t values were compared, but that was eventually removed without being adequately replaced.) Fix by storing the starting virtual address and comparing that (along with other fields) to determine if a buffer can be reused. MFC after: 3 days Sponsored by: Chelsio Communications Modified: head/sys/dev/cxgbe/tom/t4_ddp.c head/sys/dev/cxgbe/tom/t4_tom.h Modified: head/sys/dev/cxgbe/tom/t4_ddp.c ============================================================================== --- head/sys/dev/cxgbe/tom/t4_ddp.c Fri Sep 15 20:58:52 2017 (r323629) +++ head/sys/dev/cxgbe/tom/t4_ddp.c Fri Sep 15 22:40:57 2017 (r323630) @@ -1277,7 +1277,8 @@ pscmp(struct pageset *ps, struct vmspace *vm, vm_offse int pgoff, int len) { - if (ps->npages != npages || ps->offset != pgoff || ps->len != len) + if (ps->start != start || ps->npages != npages || + ps->offset != pgoff || ps->len != len) return (1); return (ps->vm != vm || ps->vm_timestamp != vm->vm_map.timestamp); @@ -1378,6 +1379,7 @@ hold_aio(struct toepcb *toep, struct kaiocb *job, stru ps->len = job->uaiocb.aio_nbytes; atomic_add_int(&vm->vm_refcnt, 1); ps->vm = vm; + ps->start = start; CTR5(KTR_CXGBE, "%s: tid %d, new pageset %p for job %p, npages %d", __func__, toep->tid, ps, job, ps->npages); Modified: head/sys/dev/cxgbe/tom/t4_tom.h ============================================================================== --- head/sys/dev/cxgbe/tom/t4_tom.h Fri Sep 15 20:58:52 2017 (r323629) +++ head/sys/dev/cxgbe/tom/t4_tom.h Fri Sep 15 22:40:57 2017 (r323630) @@ -112,6 +112,7 @@ struct pageset { int len; struct ppod_reservation prsv; struct vmspace *vm; + vm_offset_t start; u_int vm_timestamp; };
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?201709152240.v8FMevvt009106>