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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [UNIKRAFT PATCH 3/7] lib/uk9p: Use fixed-size request buffers
Use fixed-size request buffers instead of dynamically allocating new
receive and transmit buffers for each new request. This reduces the
number of calls to uk_alloc from 3 to 1 per each uk_9pdev_req_create()
call.
Allocating a request is faster by roughly 2.5 microseconds. The
previous patch in this patch series shows a 3.7us delay between read
and request_allocated. The excerpt below shows roughly 1us delay.
This performance benefit is observed at a larger scale as well (in
latency and throughput benchmarks).
Excerpt from the output traces for a read() with in-depth traces:
882362702 uk_9p_trace_read fid 2 offset 61440 count 4096
882363707 uk_9p_trace_request_allocated
882363736 uk_9p_trace_ready tag 0
882366471 uk_9p_trace_sent tag 0
882405347 uk_9p_trace_received tag 0
882405387 uk_9p_trace_read_end count 4096
Signed-off-by: Cristian Banu <cristb@xxxxxxxxx>
---
lib/uk9p/9p.c | 24 ++++++------
lib/uk9p/9pdev.c | 11 +++---
lib/uk9p/9preq.c | 76 ++++++++-----------------------------
lib/uk9p/include/uk/9pdev.h | 5 +--
lib/uk9p/include/uk/9preq.h | 31 +++++++++++++--
5 files changed, 63 insertions(+), 84 deletions(-)
diff --git a/lib/uk9p/9p.c b/lib/uk9p/9p.c
index d6ba3cf..b49ac98 100644
--- a/lib/uk9p/9p.c
+++ b/lib/uk9p/9p.c
@@ -99,7 +99,7 @@ struct uk_9preq *uk_9p_version(struct uk_9pdev *dev,
uk_9p_trace_version(dev->msize, requested);
uk_9p_str_init(&requested_str, requested);
- req = uk_9pdev_req_create(dev, UK_9P_TVERSION, __PAGE_SIZE);
+ req = uk_9pdev_req_create(dev, UK_9P_TVERSION);
if (PTRISERR(req))
return req;
@@ -154,7 +154,7 @@ struct uk_9pfid *uk_9p_attach(struct uk_9pdev *dev,
uint32_t afid,
uk_9p_trace_attach(fid->fid, afid, uname, aname, n_uname);
- req = uk_9pdev_req_create(dev, UK_9P_TATTACH, __PAGE_SIZE);
+ req = uk_9pdev_req_create(dev, UK_9P_TATTACH);
if (PTRISERR(req)) {
uk_9pdev_fid_release(fid);
return (void *)req;
@@ -193,7 +193,7 @@ int uk_9p_flush(struct uk_9pdev *dev, uint16_t oldtag)
uk_9p_trace_flush(oldtag);
- req = uk_9pdev_req_create(dev, UK_9P_TFLUSH, __PAGE_SIZE);
+ req = uk_9pdev_req_create(dev, UK_9P_TFLUSH);
if (PTRISERR(req))
return PTR2ERR(req);
@@ -234,7 +234,7 @@ struct uk_9pfid *uk_9p_walk(struct uk_9pdev *dev, struct
uk_9pfid *fid,
uk_9p_trace_walk(fid->fid, newfid->fid, name ? name : "<NULL>");
nwname = name ? 1 : 0;
- req = uk_9pdev_req_create(dev, UK_9P_TWALK, __PAGE_SIZE);
+ req = uk_9pdev_req_create(dev, UK_9P_TWALK);
if (PTRISERR(req)) {
rc = PTR2ERR(req);
goto out;
@@ -297,7 +297,7 @@ int uk_9p_open(struct uk_9pdev *dev, struct uk_9pfid *fid,
uint8_t mode)
int rc = 0;
uk_9p_trace_open(fid->fid, mode);
- req = uk_9pdev_req_create(dev, UK_9P_TOPEN, __PAGE_SIZE);
+ req = uk_9pdev_req_create(dev, UK_9P_TOPEN);
if (PTRISERR(req))
return PTR2ERR(req);
@@ -338,7 +338,7 @@ int uk_9p_create(struct uk_9pdev *dev, struct uk_9pfid *fid,
uk_9p_str_init(&name_str, name);
uk_9p_str_init(&extension_str, extension);
- req = uk_9pdev_req_create(dev, UK_9P_TCREATE, __PAGE_SIZE);
+ req = uk_9pdev_req_create(dev, UK_9P_TCREATE);
if (PTRISERR(req))
return PTR2ERR(req);
@@ -376,7 +376,7 @@ int uk_9p_remove(struct uk_9pdev *dev, struct uk_9pfid *fid)
/* The fid is considered invalid even if the remove fails. */
fid->was_removed = 1;
- req = uk_9pdev_req_create(dev, UK_9P_TREMOVE, __PAGE_SIZE);
+ req = uk_9pdev_req_create(dev, UK_9P_TREMOVE);
if (PTRISERR(req))
return PTR2ERR(req);
@@ -405,7 +405,7 @@ int uk_9p_clunk(struct uk_9pdev *dev, struct uk_9pfid *fid)
if (fid->was_removed)
return 0;
- req = uk_9pdev_req_create(dev, UK_9P_TCLUNK, __PAGE_SIZE);
+ req = uk_9pdev_req_create(dev, UK_9P_TCLUNK);
if (PTRISERR(req))
return PTR2ERR(req);
@@ -436,7 +436,7 @@ int64_t uk_9p_read(struct uk_9pdev *dev, struct uk_9pfid
*fid,
count = MIN(count, fid->iounit);
count = MIN(count, dev->msize - 11);
- req = uk_9pdev_req_create(dev, UK_9P_TREAD, __PAGE_SIZE);
+ req = uk_9pdev_req_create(dev, UK_9P_TREAD);
if (PTRISERR(req))
return PTR2ERR(req);
@@ -474,7 +474,7 @@ int64_t uk_9p_write(struct uk_9pdev *dev, struct uk_9pfid
*fid,
count = MIN(count, fid->iounit);
count = MIN(count, dev->msize - 23);
- req = uk_9pdev_req_create(dev, UK_9P_TWRITE, __PAGE_SIZE);
+ req = uk_9pdev_req_create(dev, UK_9P_TWRITE);
if (PTRISERR(req))
return PTR2ERR(req);
@@ -509,7 +509,7 @@ struct uk_9preq *uk_9p_stat(struct uk_9pdev *dev, struct
uk_9pfid *fid,
uint16_t dummy;
uk_9p_trace_stat(fid->fid);
- req = uk_9pdev_req_create(dev, UK_9P_TSTAT, __PAGE_SIZE);
+ req = uk_9pdev_req_create(dev, UK_9P_TSTAT);
if (PTRISERR(req))
return req;
@@ -542,7 +542,7 @@ int uk_9p_wstat(struct uk_9pdev *dev, struct uk_9pfid *fid,
uint16_t *dummy;
uk_9p_trace_wstat(fid->fid);
- req = uk_9pdev_req_create(dev, UK_9P_TWSTAT, __PAGE_SIZE);
+ req = uk_9pdev_req_create(dev, UK_9P_TWSTAT);
if (PTRISERR(req))
return PTR2ERR(req);
diff --git a/lib/uk9p/9pdev.c b/lib/uk9p/9pdev.c
index 1d7e09b..40a4daa 100644
--- a/lib/uk9p/9pdev.c
+++ b/lib/uk9p/9pdev.c
@@ -288,8 +288,7 @@ void uk_9pdev_xmit_notify(struct uk_9pdev *dev)
#endif
}
-struct uk_9preq *uk_9pdev_req_create(struct uk_9pdev *dev, uint8_t type,
- uint32_t size)
+struct uk_9preq *uk_9pdev_req_create(struct uk_9pdev *dev, uint8_t type)
{
struct uk_9preq *req;
int rc = 0;
@@ -298,14 +297,16 @@ struct uk_9preq *uk_9pdev_req_create(struct uk_9pdev
*dev, uint8_t type,
UK_ASSERT(dev);
- size = MIN(size, dev->msize);
-
- req = uk_9preq_alloc(dev->a, size);
+ req = uk_9preq_alloc(dev->a);
if (req == NULL) {
rc = -ENOMEM;
goto out;
}
+ /* Shouldn't exceed the msize on non-zerocopy buffers, just in case. */
+ req->recv.size = MIN(req->recv.size, dev->msize);
+ req->xmit.size = MIN(req->xmit.size, dev->msize);
+
ukplat_spin_lock_irqsave(&dev->_req_mgmt.spinlock, flags);
if (type == UK_9P_TVERSION)
tag = UK_9P_NOTAG;
diff --git a/lib/uk9p/9preq.c b/lib/uk9p/9preq.c
index 997f772..d44e684 100644
--- a/lib/uk9p/9preq.c
+++ b/lib/uk9p/9preq.c
@@ -45,51 +45,28 @@
#include <uk/wait.h>
#endif
-static int _fcall_alloc(struct uk_alloc *a, struct uk_9preq_fcall *f,
- uint32_t size)
-{
- UK_ASSERT(a);
- UK_ASSERT(f);
- UK_ASSERT(size > 0);
-
- f->buf = uk_calloc(a, size, sizeof(char));
- if (f->buf == NULL)
- return -ENOMEM;
-
- f->size = size;
- f->offset = 0;
- f->zc_buf = NULL;
- f->zc_size = 0;
- f->zc_offset = 0;
-
- return 0;
-}
-
-static void _fcall_free(struct uk_alloc *a, struct uk_9preq_fcall *f)
-{
- UK_ASSERT(a);
- UK_ASSERT(f);
-
- if (f->buf)
- uk_free(a, f->buf);
-}
-
-struct uk_9preq *uk_9preq_alloc(struct uk_alloc *a, uint32_t size)
+struct uk_9preq *uk_9preq_alloc(struct uk_alloc *a)
{
struct uk_9preq *req;
- int rc;
req = uk_calloc(a, 1, sizeof(*req));
if (req == NULL)
- goto out;
+ return NULL;
- rc = _fcall_alloc(a, &req->xmit, size);
- if (rc < 0)
- goto out_free;
+ req->xmit.buf = req->xmit_buf;
+ req->recv.buf = req->recv_buf;
+ req->xmit.size = req->recv.size = UK_9P_BUFSIZE;
+ req->xmit.zc_buf = req->recv.zc_buf = NULL;
+ req->xmit.zc_size = req->recv.zc_size = 0;
+ req->xmit.zc_offset = req->recv.zc_offset = 0;
- rc = _fcall_alloc(a, &req->recv, MAX(size, UK_9P_RERROR_MAXSIZE));
- if (rc < 0)
- goto out_free;
+ /*
+ * Assume the header has already been written.
+ * The header itself will be written on uk_9preq_ready(), when the
+ * actual message size is known.
+ */
+ req->xmit.offset = UK_9P_HEADER_SIZE;
+ req->recv.offset = 0;
UK_INIT_LIST_HEAD(&req->_list);
req->_a = a;
@@ -98,28 +75,7 @@ struct uk_9preq *uk_9preq_alloc(struct uk_alloc *a, uint32_t
size)
uk_waitq_init(&req->wq);
#endif
- /*
- * Assume the header has already been written.
- * The header itself will be written on uk_9preq_ready(), when the
- * actual message size is known.
- */
- req->xmit.offset = UK_9P_HEADER_SIZE;
-
return req;
-
-out_free:
- _fcall_free(a, &req->recv);
- _fcall_free(a, &req->xmit);
- uk_free(a, req);
-out:
- return NULL;
-}
-
-static void _req_free(struct uk_9preq *req)
-{
- _fcall_free(req->_a, &req->recv);
- _fcall_free(req->_a, &req->xmit);
- uk_free(req->_a, req);
}
void uk_9preq_get(struct uk_9preq *req)
@@ -133,7 +89,7 @@ int uk_9preq_put(struct uk_9preq *req)
last = uk_refcount_release(&req->refcount);
if (last)
- _req_free(req);
+ uk_free(req->_a, req);
return last;
}
diff --git a/lib/uk9p/include/uk/9pdev.h b/lib/uk9p/include/uk/9pdev.h
index 04ff523..1225336 100644
--- a/lib/uk9p/include/uk/9pdev.h
+++ b/lib/uk9p/include/uk/9pdev.h
@@ -114,15 +114,12 @@ void uk_9pdev_xmit_notify(struct uk_9pdev *dev);
* The Unikraft 9P Device.
* @param type
* Transmit type of the request, e.g. Tversion, Tread, and so on.
- * @param size
- * The maximum size for the receive and send buffers.
* @return
* If not an error pointer, the created request.
* Otherwise, the error in creating the request:
* - ENOMEM: No memory for the request or no available tags.
*/
-struct uk_9preq *uk_9pdev_req_create(struct uk_9pdev *dev, uint8_t type,
- uint32_t size);
+struct uk_9preq *uk_9pdev_req_create(struct uk_9pdev *dev, uint8_t type);
/**
* Looks up a request based on the given tag. This is generally used by
diff --git a/lib/uk9p/include/uk/9preq.h b/lib/uk9p/include/uk/9preq.h
index b9713e2..ed883d2 100644
--- a/lib/uk9p/include/uk/9preq.h
+++ b/lib/uk9p/include/uk/9preq.h
@@ -63,6 +63,16 @@ extern "C" {
*/
#define UK_9P_RERROR_MAXSIZE 141U
+/*
+ * The transmit and receive buffer size.
+ *
+ * The buffer size is not expected to exceed 1K: reads and writes are
+ * zero-copy; on-the-wire size of a stat structure should not exceed
+ * 1K -- its base size is 61, along with the lengths for name, uid,
+ * gid, muid and extension strings.
+ */
+#define UK_9P_BUFSIZE 1024U
+
/**
* @internal
*
@@ -125,8 +135,23 @@ enum uk_9preq_state {
* referenced anymore. A call to uk_9pdev_req_remove() is mandatory to
* correctly free this and remove it from the list of requests managed
* by the 9p device.
+ *
+ * Should fit within one page.
*/
struct uk_9preq {
+ /*
+ * Fixed-size buffer for transmit, used for most messages.
+ * Large messages will always zero-copy from the user-provided
+ * buffer (on Twrite).
+ */
+ uint8_t xmit_buf[UK_9P_BUFSIZE];
+ /*
+ * Fixed-size buffer for receive, used for most messages.
+ * Large messages will always zero-copy into the user-provided
+ * buffer (on Tread).
+ */
+ uint8_t recv_buf[UK_9P_BUFSIZE];
+ /* 2 KB offset in the structure here. */
/* Transmit fcall. */
struct uk_9preq_fcall xmit;
/* Receive fcall. */
@@ -147,6 +172,8 @@ struct uk_9preq {
#endif
};
+UK_CTASSERT(sizeof(struct uk_9preq) <= __PAGE_SIZE);
+
/**
* @internal
* Allocates a 9p request.
@@ -154,13 +181,11 @@ struct uk_9preq {
*
* @param a
* Allocator to use.
- * @param size
- * Minimum size of the receive and transmit buffers.
* @return
* - (==NULL): Out of memory.
* - (!=NULL): Successful.
*/
-struct uk_9preq *uk_9preq_alloc(struct uk_alloc *a, uint32_t size);
+struct uk_9preq *uk_9preq_alloc(struct uk_alloc *a);
/**
* Gets the 9p request, incrementing the reference count.
--
2.26.2
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