From ec8544f744fc8a6edbaf56f6485e5689709503e7 Mon Sep 17 00:00:00 2001 From: Alan Cox Date: Sun, 18 Apr 2004 05:36:37 +0000 Subject: [PATCH] Simplify the sf_buf implementation. In short, make it a trivial veneer over the direct virtual-to-physical mapping. --- sys/amd64/amd64/vm_machdep.c | 70 ++++-------------------------------- sys/amd64/include/sf_buf.h | 17 ++++----- 2 files changed, 15 insertions(+), 72 deletions(-) diff --git a/sys/amd64/amd64/vm_machdep.c b/sys/amd64/amd64/vm_machdep.c index 27047cb62689..38b359614538 100644 --- a/sys/amd64/amd64/vm_machdep.c +++ b/sys/amd64/amd64/vm_machdep.c @@ -85,19 +85,6 @@ static void cpu_reset_proxy(void); static u_int cpu_reset_proxyid; static volatile u_int cpu_reset_proxy_active; #endif -static void sf_buf_init(void *arg); -SYSINIT(sock_sf, SI_SUB_MBUF, SI_ORDER_ANY, sf_buf_init, NULL) - -/* - * Expanded sf_freelist head. Really an SLIST_HEAD() in disguise, with the - * sf_freelist head with the sf_lock mutex. - */ -static struct { - SLIST_HEAD(, sf_buf) sf_head; - struct mtx sf_lock; -} sf_freelist; - -static u_int sf_buf_alloc_want; /* * Finish a fork operation, with process p2 nearly set up. @@ -439,69 +426,24 @@ cpu_reset_real() } /* - * Allocate a pool of sf_bufs (sendfile(2) or "super-fast" if you prefer. :-)) - */ -static void -sf_buf_init(void *arg) -{ - struct sf_buf *sf_bufs; - int i; - - mtx_init(&sf_freelist.sf_lock, "sf_bufs list lock", NULL, MTX_DEF); - SLIST_INIT(&sf_freelist.sf_head); - sf_bufs = malloc(nsfbufs * sizeof(struct sf_buf), M_TEMP, - M_NOWAIT | M_ZERO); - for (i = 0; i < nsfbufs; i++) - SLIST_INSERT_HEAD(&sf_freelist.sf_head, &sf_bufs[i], free_list); - sf_buf_alloc_want = 0; -} - -/* - * Get an sf_buf from the freelist. Will block if none are available. + * Allocate an sf_buf for the given vm_page. On this machine, however, there + * is no sf_buf object. Instead, an opaque pointer to the given vm_page is + * returned. */ struct sf_buf * sf_buf_alloc(struct vm_page *m, int pri) { - struct sf_buf *sf; - int error; - mtx_lock(&sf_freelist.sf_lock); - while ((sf = SLIST_FIRST(&sf_freelist.sf_head)) == NULL) { - sf_buf_alloc_want++; - mbstat.sf_allocwait++; - error = msleep(&sf_freelist, &sf_freelist.sf_lock, PVM | pri, - "sfbufa", 0); - sf_buf_alloc_want--; - - /* - * If we got a signal, don't risk going back to sleep. - */ - if (error) - break; - } - if (sf != NULL) { - SLIST_REMOVE_HEAD(&sf_freelist.sf_head, free_list); - sf->m = m; - nsfbufsused++; - nsfbufspeak = imax(nsfbufspeak, nsfbufsused); - } - mtx_unlock(&sf_freelist.sf_lock); - return (sf); + return ((struct sf_buf *)m); } /* - * Release resources back to the system. + * Free the sf_buf. In fact, do nothing because there are no resources + * associated with the sf_buf. */ void sf_buf_free(struct sf_buf *sf) { - - mtx_lock(&sf_freelist.sf_lock); - SLIST_INSERT_HEAD(&sf_freelist.sf_head, sf, free_list); - nsfbufsused--; - if (sf_buf_alloc_want > 0) - wakeup_one(&sf_freelist); - mtx_unlock(&sf_freelist.sf_lock); } /* diff --git a/sys/amd64/include/sf_buf.h b/sys/amd64/include/sf_buf.h index 7fd1a64c5dd9..aacd6c5652e0 100644 --- a/sys/amd64/include/sf_buf.h +++ b/sys/amd64/include/sf_buf.h @@ -29,29 +29,30 @@ #ifndef _MACHINE_SF_BUF_H_ #define _MACHINE_SF_BUF_H_ -#include - #include #include #include -struct sf_buf { - SLIST_ENTRY(sf_buf) free_list; /* list of free buffer slots */ - vm_page_t m; /* currently mapped page */ -}; +/* + * On this machine, the only purpose for which sf_buf is used is to implement + * an opaque pointer required by the machine-independent parts of the kernel. + * That pointer references the vm_page that is "mapped" by the sf_buf. The + * actual mapping is provided by the direct virtual-to-physical mapping. + */ +struct sf_buf; static __inline vm_offset_t sf_buf_kva(struct sf_buf *sf) { - return (PHYS_TO_DMAP(sf->m->phys_addr)); + return (PHYS_TO_DMAP(VM_PAGE_TO_PHYS((vm_page_t)sf))); } static __inline vm_page_t sf_buf_page(struct sf_buf *sf) { - return (sf->m); + return ((vm_page_t)sf); } #endif /* !_MACHINE_SF_BUF_H_ */