Date: Wed, 16 Dec 2015 22:48:32 +0000 (UTC) From: Gleb Smirnoff <glebius@FreeBSD.org> To: src-committers@freebsd.org, svn-src-projects@freebsd.org Subject: svn commit: r292381 - in projects/sendfile: sys/kern sys/sys usr.bin/netstat Message-ID: <201512162248.tBGMmWVd005114@repo.freebsd.org>
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Author: glebius Date: Wed Dec 16 22:48:32 2015 New Revision: 292381 URL: https://svnweb.freebsd.org/changeset/base/292381 Log: Provide new behavior of SF_NODISKIO flag - abandon operation upon encounter of a busy page. A retry after a short period of time is adviced. This behavior is already documented in lib/libc/sys/sendfile.2 of this branch. Modified: projects/sendfile/sys/kern/uipc_syscalls.c projects/sendfile/sys/sys/sf_buf.h projects/sendfile/usr.bin/netstat/mbuf.c Modified: projects/sendfile/sys/kern/uipc_syscalls.c ============================================================================== --- projects/sendfile/sys/kern/uipc_syscalls.c Wed Dec 16 22:34:41 2015 (r292380) +++ projects/sendfile/sys/kern/uipc_syscalls.c Wed Dec 16 22:48:32 2015 (r292381) @@ -2138,21 +2138,28 @@ sf_iodone(void *arg, vm_page_t *pg, int */ static int sendfile_swapin(vm_object_t obj, struct sf_io *sfio, off_t off, off_t len, - int npages, int rhpages) + int npages, int rhpages, int flags) { vm_page_t *pa = sfio->pa; int nios; nios = 0; - VM_OBJECT_WLOCK(obj); + flags = (flags & SF_NODISKIO) ? VM_ALLOC_NOWAIT : 0; /* * First grab all the pages and wire them. Note that we grab * only required pages. Readahead pages are dealt with later. */ - for (int i = 0; i < npages; i++) + VM_OBJECT_WLOCK(obj); + for (int i = 0; i < npages; i++) { pa[i] = vm_page_grab(obj, OFF_TO_IDX(vmoff(i, off)), - VM_ALLOC_WIRED | VM_ALLOC_NORMAL); + VM_ALLOC_WIRED | VM_ALLOC_NORMAL | flags); + if (pa[i] == NULL) { + npages = i; + rhpages = 0; + break; + } + } for (int i = 0; i < npages;) { int j, a, count, rv; @@ -2552,7 +2559,8 @@ retry_space: refcount_init(&sfio->nios, 1); sfio->error = 0; - nios = sendfile_swapin(obj, sfio, off, space, npages, rhpages); + nios = sendfile_swapin(obj, sfio, off, space, npages, rhpages, + flags); /* * Loop and construct maximum sized mbuf chain to be bulk @@ -2563,6 +2571,18 @@ retry_space: struct mbuf *m0; /* + * If a page wasn't grabbed successfully, then + * trim the array. Can happen only with SF_NODISKIO. + */ + if (pa[i] == NULL) { + SFSTAT_INC(sf_busy); + fixspace(npages, i, off, &space); + npages = i; + softerr = EBUSY; + break; + } + + /* * Get a sendfile buf. When allocating the * first buffer for mbuf chain, we usually * wait as long as necessary, but this wait Modified: projects/sendfile/sys/sys/sf_buf.h ============================================================================== --- projects/sendfile/sys/sys/sf_buf.h Wed Dec 16 22:34:41 2015 (r292380) +++ projects/sendfile/sys/sys/sf_buf.h Wed Dec 16 22:48:32 2015 (r292381) @@ -38,6 +38,7 @@ struct sfstat { /* sendfile statistic uint64_t sf_pages_valid; /* pages were valid for a request */ uint64_t sf_rhpages_requested; /* readahead pages requested */ uint64_t sf_rhpages_read; /* readahead pages read */ + uint64_t sf_busy; /* times aborted on a busy page */ uint64_t sf_allocfail; /* times sfbuf allocation failed */ uint64_t sf_allocwait; /* times sfbuf allocation had to wait */ }; Modified: projects/sendfile/usr.bin/netstat/mbuf.c ============================================================================== --- projects/sendfile/usr.bin/netstat/mbuf.c Wed Dec 16 22:34:41 2015 (r292380) +++ projects/sendfile/usr.bin/netstat/mbuf.c Wed Dec 16 22:48:32 2015 (r292381) @@ -346,6 +346,9 @@ mbpr(void *kvmd, u_long mbaddr) xo_emit("{:sendfile-readahead/%ju} " "{N:pages were read ahead by sendfile}\n", (uintmax_t)sfstat.sf_rhpages_read); + xo_emit("{:sendfile-busy-encounters/%ju} " + "{N:times sendfile encountered an already busy page}\n", + (uintmax_t)sfstat.sf_busy); xo_emit("{:sfbufs-alloc-failed/%ju} {N:requests for sfbufs denied}\n", (uintmax_t)sfstat.sf_allocfail); xo_emit("{:sfbufs-alloc-wait/%ju} {N:requests for sfbufs delayed}\n",
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